You would have to continuously monitor everything, everywhere; before the internet, in the 80s, it was easy for us to get porn (mags/vhs), weed, all kinds of books that glorify death or whatever, music in that similar vain. Hell, they even had and read from a bible in some schools then; talk about indoctrination of often scary fiction. Some kids had different parents so to not allow us to see or get our hands on these things, parents and teachers would need sit with us every waking moment; it's not possible (or healthy imho). With access to a phone or laptop, all bets are off: everything is there, doesn't matter what restraints are in place; kids know how to install vpns, pick birthdates, use torrent, or, more innocent, go to a forum (these days social media but forums are still there) about something they love and go to other parts of the same forum where other stuff happens.
Be good parents, educate about what happens in the world including that people irl but definitely online might not be serious about what they say and that you should not take anything without critical thought. And for stuff that will happen anyway; sex, drugs etc, make sure it's a controlled environment as much as possible. Not much more you can do to protect from the big, bad world.
Chat bots are similarly genies that are not possible to keep in, no matter what levels or restraint or law are put in place; you can torrent ollama or whatever with llama 3.3 locally. There are easy to get nsfw bots everywhere, including on decentralised shares. It is not possible to prevent them talking about anything as they do not understand anything; they helpfully generate stuff which is a great invention and I use them all the time, but they lie and tell strange things sometimes. People do too, only people would have a reason maybe; to get a reaction, to be mean etc; doubt you could sue them in a similar case. Of course a big company would need to do something to try to prevent is: they cannot (as said above), so they can just make character ai 18+ with Cc payment in their name as kyc (then the parents have a problem if that happens you would think) and cover their asses; plenty commercial and free ones kids will get instead. And some of those are far 'worse'.