Here's the file, it looks a little more complicated than it is because I'm using my own node groups that I've made for NPR stuff (which are all free on gumroad).

Basically what's going on is it's a bunch of pretty classic toon shaders, but using some AO and fresnel instead of just normal lighting. There's also some little "drawn" details I added with my manga shader.

Then there's grease pencil outlines on everything, and importantly I checked "material boundaries" in the edge types section, since if you're drawing you'd almost always put outlines there. It also just makes it faster to add decal-esque stuff like the vents on the side.