Posts can have tags, kind of, just like we would add a tag in a social media platform, within the post itself:
I use this approach on my community, I then have a custom API endpoint to get all posts with a given mentioned tag to present them as a “timeline” of the tag on my main website (here I’m listing all posts mentioning #dune-imperium):
What would be useful IMO is adding this “mentioned tag” filter to the Search page, which would render a similar view. It’s the main place where we can list individual posts so it makes sense to have this feature there.
If you think about it, even if you add tags to replies with a custom post field, how would you filter by them or show them outside the topic itself?
If you have a specific use case that wouldn’t be covered by just adding tags to a post body, tell us and we can try figuring something out.