The best idea imho is the assumption that people have some intelligence. I know, it's an utopia. But, well... Give them a way to block users. Help law enforcement when something actually criminal happens. For the rest, just let it happen, and let the people deal with it. As in real life. There is no other chance. Making the masses even more stupid than they are today (by hiding reality from them) is not the way to go. It never was. Let people interact with each other on their own. There cannot be a higher instance which 'manages' that in some way. Censorship isn't better when you call it 'moderation'. And don't declare everything as a harassment or worse. It's just a facet of communication to also communicate unfortunate things. People are veeeery sensitive plants since some time.

And again, for actual crime, it's not the forum moderators at all who should lead some actions. That would really be problematic.