How do I change the age of my child on family sharing
Can I change the age of my child on the family sharing?
iPhone XS, iOS 16
If the birthdate is currently set to 13 or older, see the "Change a birth date for a child" section of Update the birth date associated with your Apple ID - Apple Support
If the birthdate is currently set to under 13, see the following from that support article:
If you need to change the birth date for a child, contact Apple Support.