Ones that prevent the scaling itself:

No algorithmic recommendation.

No mixing between known users (friends, followers etc.), recommended users (swipe feed) and advertised content.

No publication of user content. It's social media, not global media.

I posit that these points will be enough to curtail most of social media ills. Don't allow recommendation of slop and there will be a similar reduction in production. There will still be the village idiot that shares slop content, but their reach is limited since they have to actively persuade people to their message, rather than be recommended for being psychologically stimulating.