The Plugin changes the format to DD.MM.YYYY for the date field
and it's structure field preview
.
With this example it should be easy to adapt the format to your needs.
dayjs is used to work with dateformats https://github.com/iamkun/dayjs
Tested with Kirby 3.0
Download and copy this repository to /site/plugins/k3-date-format
git submodule add https://github.com/mullema/k3-date-format.git site/plugins/k3-date-format
composer require mullema/k3-date-format