I know I've beat this horse into the ground, but....I really wish there were more third party Mastodon Admin tools.
There's a couple. One for sure, I've heard about another but I couldn't find it again.
However, there's nothing that I know of, that will let you automatically remove entire hashtags of content from your instance or keywords.
Some contributors are building moderation tools, but I don't think it includes automation like this. Kinda weird that Mastodon Devs expect all of us moderators and admins to visually encounter offending content before removing it. That's SO weird... "If you can't see the Loli content, it doesn't exist!!!" Makes no sense....😳