Sites that are most successful have COCs that are clearly defined, and free of micromanagement.
The old "be nice" policy was more that adequate, because that means that EVERYBODY has to be nice to EVERYONE ELSE.
Then things changed, and I got kicked out for a while for using the term "autistic shrieking", despite the fact that I'm autistic. Various people stared getting offended on the behalf of other people, and much silliness ensued.