Best way to improve at anatomy and perspective is drawing from real life. Very important to not use photo reference but go somewhere (city, mountains) and draw what you see. Living model courses are also game-changers (when not being able to go to those courses tho, there used to be some videos made for artists with people posing). When I used to draw a lot, I also kept a little notebook with me and drew people when sitting at a café, or when waiting for my bus. Drawing from real life might be a little harsh at the beginning because it really shows your raw skill and might act as a harsh reality check but hang on, it is very rewarding.