How do u change ur age if ur already 13?

Hi Ellliot654,

welcome to the Apple (user-to-user) Community.

If your birth-date in your Apple ID is incorrect:

and

If it shows you are less than 13, a family sharing organizer would need to contact Apple in order to change that:

Else if it shows you are over 13, and is just incorrect::

How to: Update the birth date associated with your Apple ID - Apple Support

All the best :-)