and if they're just old enough to follow instructions from an older cousin, an online predator, or to hand over their phone to a candy waving dubious third party for a "roblox coin hack" ?

How did we get here from OS age reporting? I don't see how age reporting is going to stop any of those 3 things - or indeed any technical set of controls.

If the fear is kids communicating with people, I might suggest giving them a phone and an internet connection is a poor start whatever happens next. They're communication tools. They're going to use them to communicate.