#mastodon users: content warnings dont exist out of mastodon, like literally, the programs don't have it.  So asking for them won't help even if the person doesn't mind putting CWs on stuff.

Consider asking people to #nsfw tags on stuff that is truly objectionable - it is the universal fediverse sensitive content tag.  Any message that is tagged #nsfw should be spoilered on most of the fediverse at this point.