Let's say you have completed a novel. Since you're not totally naive, you have also complete a few drafts, where with "few" I mean at least more than two.
You are at a point that your book seems good; while it could certainly be better, you - the author - need some external input on how to fix the last, hopefully few, issues left. Let's imagine that doing another draft by yourself is not feasible at the moment just for the sake of the question.
Do you call in a professional editor or you start querying to publishers?
I understand that this might seem like a no-brainer. If you book isn't the best it could be, you should (ideally) query. Yet, in my limited understanding, major publishers are supposed to give you at least some kind of editing service.
Related: At what point does an author deal with an editor?
Edit: I've just noticed a very similar question from 8 years ago. I'm adding it as related. My question seems slightly different, but I may be wrong; please see if it's a duplicate.