Just have age verification on an ISP-level at this point.
That's a little bit of a joke. But think about it. Kids don't just find Tiktok hidden among the grass. Their parents give them a phone, give them a computer, a data plan and a wifi password without any parental controls. Then they blame Tiktok when their child commits suicide (possibly had nothing to do with tiktok).
I think maybe have ISPs become the accountable ones. Have them automatically enable parental controls, or emit a second network for kids, and add a waiver to the settings when you go to disable parental controls absolving them of any accountability and placing it on the parents.