One that stands out to me are the optional notes above the comment box for each community.

On piefed.social I’ve used this to put a note on every beehaw.org community about the ‘good vibes only’ nature of that instance and one community on lemmy.ml has a note about the unusual mostly-unwritten moderation policies employed there.

I like this idea, because it would serve as a last second warning to me(and others) that I might be at risk of participating with tankies.