List off topic posts for easy moderation

Is there a way to analyse chains of posts whether they are off-topic with respect to the theme/thread and first post ?
I think of “this topic resembles…” which indicates there is a db of similarity existing.
There might be an evaluation of flags made by users in the past.
There might be an evaluation of moderated moves in the past.
see also
There might be a KI or NLP to work the posts and identify hits and misses of the theme. This could help moderation and clean the forum.