to modify the cage of child more than 14 year
I want to change the birth date of my iPhone
iPhone 11 Pro
Question marked as
If you mean a person, read this support article about how to update the birth date associated with an Apple ID: Update the birth date associated with your Apple ID - Apple Support
There's different ways to change the age on an account depending upon the age of the person, their target age, and the country's age definition of "child".