Update field with a first day of month (beginner)

Scriptcase 9 General
#1

Hi, I need update a field with de first day of same month of date in field.
Example
{date_1} = ‘26/08/2023’
must be ‘01/08/2023’.
{date_1} = ‘25/04/2023’
must be ‘01/04/2023’.

Does anybody can help ?
thanks

#2 
date('Y-m-01');

So you can modify as you want.