My kids are younger but I'm having issues with them and YouTube. I have YouTube completely blocked on their personal device, but I can't do anything about their school issued Chromebook. In the end I have to completely block the school laptops from the internet at home, otherwise they go from a video about reptiles quickly into toy unboxing, fail video reactions, etc. In the end I have to continuously block and unblock websites and devices so they can do their homework. It's maddening, especially since there is so much educational material on YouTube. It's a losing battle.

My son is still young, so enforcing boundaries is much easier (easier as in successful, the emotional disregulation is still there of course).

It’s not easy. Do your best. Try to actively support broadening their experiences with (hopefully) the outcome that they expand their interests. I think the needed thing here is not necessarily teetotaling, but finding something better to do than consuming media all the time.