Hi @Heinrichxx ,
You can use the expression formatDateTime(value, 'dd-MM-yyyy').
In your 'Send email' action, when you select the dynamic content, change it to 'Expressions' and paste the method above. Change the 'value' for the dynamic content of the date that you want to format. Also, you can change the separators ('-') by any other symbol.

If you find any trouble to implement this expression, let me know and I help you!