I’m in agreement with most said here. Users of other instances wouldn’t know of our TOS and rules generally. But also, our TOS is for access to “the website” i.e. lemmy.world. Users on other instances are not using this website, technically. They are accessing information originated here. It’s a complicated situation because of the nature of federation.

Personally, I would try to manage LW users specifically when it comes to age restrictions as those are the ones who agreed to our TOS and age requirement. So basically, if a LW user is known to be under 18, take action, and if a user from another instance openly says they are under 18, then take action. Explanation is up to you.