Basically any word or short phrase I can think of to mean “a lot of muscle” also implies skinny or almost no fat. Fit, or lithe bring to mind more a track athlete’s body, and buff, ripped, jacked, muscular, ect. generally are though of more like a body builder. The closest thing I can think of is dad-bod but thats obviously still pretty far off as well as being male-specific. Is there even an English word for this?
Or sort phrase. The sort of thing you might introduce a minor character in a book with. Something that would fit in a phrase like, “He was a tall, buff man.”
i think you already have a bunch in the OP - just choose what fits best and add what will cancel misinterpretations of your words.