diff --git a/src/plugins/vis_types/heatmap/public/to_ast.ts b/src/plugins/vis_types/heatmap/public/to_ast.ts
index 22fb581858040..5b52ab1feeb3a 100644
--- a/src/plugins/vis_types/heatmap/public/to_ast.ts
+++ b/src/plugins/vis_types/heatmap/public/to_ast.ts
@@ -6,14 +6,8 @@
  * Side Public License, v 1.
  */
 
-import {
-  VisToExpressionAst,
-  getVisSchemas,
-  SchemaConfig,
-  LegendSizeToPixels,
-} from '@kbn/visualizations-plugin/public';
+import { VisToExpressionAst, getVisSchemas, SchemaConfig } from '@kbn/visualizations-plugin/public';
 import { buildExpression, buildExpressionFunction } from '@kbn/expressions-plugin/public';
-import { DEFAULT_LEGEND_SIZE } from '@kbn/visualizations-plugin/public';
 import { getStopsWithColorsFromRanges, getStopsWithColorsFromColorsNumber } from './utils/palette';
 import type { HeatmapVisParams } from './types';
 import { getEsaggsFn } from './to_ast_esaggs';
@@ -26,7 +20,7 @@ const prepareLegend = (params: HeatmapVisParams) => {
     position: params.legendPosition,
     shouldTruncate: params.truncateLegend ?? true,
     maxLines: params.maxLegendLines ?? 1,
-    legendSize: LegendSizeToPixels[params.legendSize ?? DEFAULT_LEGEND_SIZE],
+    legendSize: params.legendSize,
   });
 
   return buildExpression([legend]);
diff --git a/src/plugins/vis_types/pie/public/__snapshots__/to_ast.test.ts.snap b/src/plugins/vis_types/pie/public/__snapshots__/to_ast.test.ts.snap
index 89863518c2f14..5b8bd613609f9 100644
--- a/src/plugins/vis_types/pie/public/__snapshots__/to_ast.test.ts.snap
+++ b/src/plugins/vis_types/pie/public/__snapshots__/to_ast.test.ts.snap
@@ -94,7 +94,7 @@ Object {
           "right",
         ],
         "legendSize": Array [
-          130,
+          "large",
         ],
         "metric": Array [
           Object {
diff --git a/src/plugins/vis_types/pie/public/sample_vis.test.mocks.ts b/src/plugins/vis_types/pie/public/sample_vis.test.mocks.ts
index f8836f208d916..4c638689ca310 100644
--- a/src/plugins/vis_types/pie/public/sample_vis.test.mocks.ts
+++ b/src/plugins/vis_types/pie/public/sample_vis.test.mocks.ts
@@ -7,6 +7,7 @@
  */
 
 import { LegendDisplay } from '@kbn/expression-partition-vis-plugin/common';
+import { LegendSize } from '@kbn/visualizations-plugin/common';
 
 export const samplePieVis = {
   type: {
@@ -142,6 +143,7 @@ export const samplePieVis = {
     addTooltip: true,
     legendDisplay: LegendDisplay.SHOW,
     legendPosition: 'right',
+    legendSize: LegendSize.LARGE,
     isDonut: true,
     labels: {
       show: true,
diff --git a/src/plugins/vis_types/pie/public/to_ast.ts b/src/plugins/vis_types/pie/public/to_ast.ts
index e6560ea6f70ff..d6a9876f79e72 100644
--- a/src/plugins/vis_types/pie/public/to_ast.ts
+++ b/src/plugins/vis_types/pie/public/to_ast.ts
@@ -7,13 +7,7 @@
  */
 
 import type { PaletteOutput } from '@kbn/coloring';
-import {
-  getVisSchemas,
-  VisToExpressionAst,
-  SchemaConfig,
-  DEFAULT_LEGEND_SIZE,
-  LegendSizeToPixels,
-} from '@kbn/visualizations-plugin/public';
+import { getVisSchemas, VisToExpressionAst, SchemaConfig } from '@kbn/visualizations-plugin/public';
 import { buildExpression, buildExpressionFunction } from '@kbn/expressions-plugin/public';
 import {
   PIE_VIS_EXPRESSION_NAME,
@@ -71,7 +65,7 @@ export const toExpressionAst: VisToExpressionAst<PartitionVisParams> = async (vi
     nestedLegend: vis.params?.nestedLegend ?? false,
     truncateLegend: vis.params.truncateLegend,
     maxLegendLines: vis.params.maxLegendLines,
-    legendSize: LegendSizeToPixels[vis.params?.legendSize ?? DEFAULT_LEGEND_SIZE],
+    legendSize: vis.params?.legendSize,
     distinctColors: vis.params?.distinctColors,
     isDonut: vis.params.isDonut ?? false,
     emptySizeRatio: vis.params.emptySizeRatio,
diff --git a/src/plugins/vis_types/xy/public/__snapshots__/to_ast.test.ts.snap b/src/plugins/vis_types/xy/public/__snapshots__/to_ast.test.ts.snap
index 6505b5e6250b8..048b07dbf34ed 100644
--- a/src/plugins/vis_types/xy/public/__snapshots__/to_ast.test.ts.snap
+++ b/src/plugins/vis_types/xy/public/__snapshots__/to_ast.test.ts.snap
@@ -33,7 +33,7 @@ Object {
       "top",
     ],
     "legendSize": Array [
-      130,
+      "small",
     ],
     "maxLegendLines": Array [
       1,
diff --git a/src/plugins/vis_types/xy/public/expression_functions/xy_vis_fn.ts b/src/plugins/vis_types/xy/public/expression_functions/xy_vis_fn.ts
index 96c4ab112caf1..2f331b7fa95b8 100644
--- a/src/plugins/vis_types/xy/public/expression_functions/xy_vis_fn.ts
+++ b/src/plugins/vis_types/xy/public/expression_functions/xy_vis_fn.ts
@@ -13,7 +13,12 @@ import type {
   Datatable,
   Render,
 } from '@kbn/expressions-plugin/common';
-import { prepareLogTable, Dimension } from '@kbn/visualizations-plugin/public';
+import {
+  prepareLogTable,
+  Dimension,
+  DEFAULT_LEGEND_SIZE,
+  LegendSize,
+} from '@kbn/visualizations-plugin/public';
 import type { ChartType } from '../../common';
 import type { VisParams, XYVisConfig } from '../types';
 
@@ -73,10 +78,19 @@ export const visTypeXyVisFn = (): VisTypeXyExpressionFunctionDefinition => ({
       }),
     },
     legendSize: {
-      types: ['number'],
-      help: i18n.translate('visTypeXy.function.args.args.legendSize.help', {
-        defaultMessage: 'Specifies the legend size in pixels.',
+      types: ['string'],
+      default: DEFAULT_LEGEND_SIZE,
+      help: i18n.translate('expressionHeatmap.function.args.legendSize.help', {
+        defaultMessage: 'Specifies the legend size.',
       }),
+      options: [
+        LegendSize.AUTO,
+        LegendSize.SMALL,
+        LegendSize.MEDIUM,
+        LegendSize.LARGE,
+        LegendSize.EXTRA_LARGE,
+      ],
+      strict: true,
     },
     addLegend: {
       types: ['boolean'],
diff --git a/src/plugins/vis_types/xy/public/sample_vis.test.mocks.ts b/src/plugins/vis_types/xy/public/sample_vis.test.mocks.ts
index 436a284b1657a..3c1d87d2efc3c 100644
--- a/src/plugins/vis_types/xy/public/sample_vis.test.mocks.ts
+++ b/src/plugins/vis_types/xy/public/sample_vis.test.mocks.ts
@@ -5,6 +5,9 @@
  * in compliance with, at your election, the Elastic License 2.0 or the Server
  * Side Public License, v 1.
  */
+
+import { LegendSize } from '@kbn/visualizations-plugin/common';
+
 export const sampleAreaVis = {
   type: {
     name: 'area',
@@ -282,6 +285,7 @@ export const sampleAreaVis = {
     addTooltip: true,
     addLegend: true,
     legendPosition: 'top',
+    legendSize: LegendSize.SMALL,
     times: [],
     addTimeMarker: false,
     truncateLegend: true,
diff --git a/src/plugins/vis_types/xy/public/to_ast.ts b/src/plugins/vis_types/xy/public/to_ast.ts
index 82e01a3ca60cd..bf2ca297f9f38 100644
--- a/src/plugins/vis_types/xy/public/to_ast.ts
+++ b/src/plugins/vis_types/xy/public/to_ast.ts
@@ -13,8 +13,6 @@ import {
   getVisSchemas,
   DateHistogramParams,
   HistogramParams,
-  DEFAULT_LEGEND_SIZE,
-  LegendSizeToPixels,
 } from '@kbn/visualizations-plugin/public';
 import { buildExpression, buildExpressionFunction } from '@kbn/expressions-plugin/public';
 import { BUCKET_TYPES } from '@kbn/data-plugin/public';
@@ -212,7 +210,7 @@ export const toExpressionAst: VisToExpressionAst<VisParams> = async (vis, params
     addTimeMarker: vis.params.addTimeMarker,
     truncateLegend: vis.params.truncateLegend,
     maxLegendLines: vis.params.maxLegendLines,
-    legendSize: LegendSizeToPixels[vis.params.legendSize ?? DEFAULT_LEGEND_SIZE],
+    legendSize: vis.params.legendSize,
     addLegend: vis.params.addLegend,
     addTooltip: vis.params.addTooltip,
     legendPosition: vis.params.legendPosition,
diff --git a/src/plugins/vis_types/xy/public/types/param.ts b/src/plugins/vis_types/xy/public/types/param.ts
index 4d55ae1563aa1..a491efad97fcb 100644
--- a/src/plugins/vis_types/xy/public/types/param.ts
+++ b/src/plugins/vis_types/xy/public/types/param.ts
@@ -166,7 +166,7 @@ export interface XYVisConfig {
   addTimeMarker: boolean;
   truncateLegend: boolean;
   maxLegendLines: number;
-  legendSize?: number;
+  legendSize?: LegendSize;
   orderBucketsBySum?: boolean;
   labels: ExpressionValueLabel;
   thresholdLine: ExpressionValueThresholdLine;
diff --git a/src/plugins/vis_types/xy/public/vis_component.tsx b/src/plugins/vis_types/xy/public/vis_component.tsx
index 7c0636ab284fb..a744841601a67 100644
--- a/src/plugins/vis_types/xy/public/vis_component.tsx
+++ b/src/plugins/vis_types/xy/public/vis_component.tsx
@@ -33,7 +33,11 @@ import {
   useActiveCursor,
 } from '@kbn/charts-plugin/public';
 import { Datatable, IInterpreterRenderHandlers } from '@kbn/expressions-plugin/public';
-import type { PersistedState } from '@kbn/visualizations-plugin/public';
+import {
+  DEFAULT_LEGEND_SIZE,
+  LegendSizeToPixels,
+  PersistedState,
+} from '@kbn/visualizations-plugin/public';
 import { VisParams } from './types';
 import {
   getAdjustedDomain,
@@ -361,7 +365,7 @@ const VisComponent = (props: VisComponentProps) => {
             tooltip: { visible: syncTooltips, placement: Placement.Right },
           }}
           legendPosition={legendPosition}
-          legendSize={visParams.legendSize}
+          legendSize={LegendSizeToPixels[visParams.legendSize ?? DEFAULT_LEGEND_SIZE]}
           xDomain={xDomain}
           adjustedXDomain={adjustedXDomain}
           legendColorPicker={legendColorPicker}