For me, it was really stumbling onto Feng Zhu's channel that changed things: https://www.youtube.com/user/FZDSCHOOL/videos The big change is more at a metacognitive level, which was to understand that you could view 'art' purely as a technical field, not something that involved artistic sense or talent. So he goes other detail density distribution, color theory, perspective, etc. The video content also helps getting a morale boost to grind through the exercises.

I would say you would not really benefit from actual dedicated courses for the first 2 years (assuming you practice with hobby-time and not full time); you have so much to learn that y ou will do big progress just doing standard exercises. Dedicated tutoring is good, but it's probably easier to get decent feedback IRL as opposed to online courses (unless you pay a fortune, it's easier to get advice from good local artists). James Gurney and Nathan Fowkes are great references.

(For reference I post some of my stuff here: https://twitter.com/wooliondraws I'm not close to any mastery, but given the amount of time I can sink into this hobby since 2015, I'm now fairly happy.).

Although there's no miracle: FZD school claims to bring people from beginner to pro-level in 3 years, but at the price of heart attacks at 30 years old for some of them.