The laws involving age are exactly the issue here. What if someone has some developmental disorder that strands their body and mind at the developmental age of 12, despite being much older. Should they be able to drink, drive and vote? Should everybody retire at the same age despite differences in health?

It can't hurt to rethink some of those old assumptions. Of course changing your age is a stupid idea. But maybe identifying certain developmental phases and making it possible, in extreme cases, to assign someone to a more appropriate phase, might make it easier for the law to treat them the way they actually are, rather than the way the average person of their age is.

In programmer terms: don't rely on a magic number, but capture what the number means.