@millihertz
I think you can do it as instance admin on Pleroma using MRF policies:
Pleroma.Web.ActivityPub.MRF.TagPolicy: Applies policies to individual users based on tags, which can be set using pleroma-fe/admin-fe/any other app that supports Pleroma Admin API. For example it allows marking posts from individual users nsfw (sensitive).
I'm not sure there is something similar for Masto 🤷