[tom1337]

Apple actually has this already. For countries that support IDs in Apple Wallet there is a "Verify with Wallet API" [1] and for other countries the app developer can get the age range from the iCloud Account [2] - but that is not verified with any legal authority and only based on user input.

1) https://developer.apple.com/wallet/get-started-with-verify-w... 2) https://developer.apple.com/documentation/declaredagerange/