/ic/ - Artwork/Critique

Of course. Look up "michelangelo study for" or "raphael study for" etc and you will see their sketches and janky (for a master) practice work.
harder to find explicit construction of boxes and cylinders but if you watch karl gnass, vilppu or steve huston doing a master study they will show you the underlying structure that the masters put into their figures and it is full of boxes, cylinders and spheres.