I’m sure there are communities out there dedicated to singing technique, but in this case, I would strongly advise trying to find a good teacher that you can see in person.
A great guitar teacher is probably the best way to learn, but isn’t a requirement. Plenty of people have figured it out through recordings, books, videos, etc.
Singing is different than guitar. Unless you played another string instrument, you probably never had any experience playing a fretboard or picking until you picked up a guitar. It’s always easier to learn something when you’re starting from nothing.
But everyone has been using their vocal cords their entire life, and there’s a lot of engrained habits – many of them probably bad. You have to re-learn how to use your body in order to sing properly. And a live teacher can provide instant, tactile feedback that no book or online community possibly can. It’s like Olympic weightlifting. Can you learn it on your own? Possibly. But it’ll be much, much easier with a qualified coach (and almost impossible to reach the highest levels without one).
You’re definitely correct that there are different schools of thought around proper singing technique. Finding the right teacher for you will require some digging. As a longtime music teacher, it is totally fair game to interview any teacher before handing over your money. They should be willing to discuss their pedagogical philosophies, their training and qualifications, success stories, etc. Ideally, you’d get examples where they took someone at your current level, and helped them reach the level you want to attain.
Good luck!