How to switch to german Format DD.MM.YYY

[SGD-DEV]

How to switch en-GB to de-DE
from MM/DD/YYYY 11/15/2023
to DD.MM.YYYYY 15.11.2023

in this Function?

format: function (dt) {
return (dt.getMonth() + 1) + '.' + dt.getDate() + '.' + dt.getFullYear();
},

Or other way?