This sketch is all about exaggerated depth. I’m reminded of one of my all time favorite Alex Toth comics, ” Crime and Punishment”, issue #66, published in 1954. He was tasked with drawing a 3D comic, but the publisher was too cheap to do the process, so he had to fake it by exaggerating the depth in every panel. The entire issue is reprinted in “The Comics Journal” issue 262, published in 2004.
Unlike master Toth, I didn’t spot any blacks in this drawing.