What kind of editing are you talking about, and on what kind of project? I mean, are you planning to self-publish, or try to get an agent and publish traditionally?
If you're publishing traditionally, obviously you will have an actual editor whose job it is to edit your book, and who will have bought your book because he or she wanted it, and because it's right for the imprint they work for (crime, gardening etc).
Though to get to that point you will need to impress an agent with your work to the point where they think they can sell it to an editor. I assume some people do pay someone to look at their MS before they query agents -- and there are various manuscript consultants out there. If you look at this page, one of them groups what they offer into different categories, depending on what stage you're at, anything from developmental editing to a copy-edit:
https://literaryconsultancy.co.uk/editorial-services/start-here/
But none of that is in any way necessary. Neither is doing a writing course.
Many people just write an MS, get it as good as they can make it, possibly exchange critiques in a writers' group or have it read by an honest friend, and send an excerpt off to agents.
ETA I have nothing to do with The Literary Consultancy, I should say! I've never used them for anything, and only put up the link because it shows what one editorial service offers writers who want different things.