

A parent can flag an account of their children, that the child has to accept. They would of course do this together sitting next to each other, so the child has no choice but to accept. Then, the parent can control the content the child sees.
Honestly age verification other than ID checks will never work. But to send your ID to the owner of an instance is of a whole other level, that the people who join / have joined and even the instance owners are probably unwilling to accept. And they wouln’t be wrong for that.
But god forbid I use ad blocker on Facebook