shhh, don't tell anyone but i actually do know.
in blender, make sure all materials u use have toon shading, then in compositing add a color ramp (for sharp edges; tweak it to your liking), give it constant interpolation, plug the render layer alpha into it, then add a "set alpha" node and plug the color of the ramp into the alpha and render layer color into the color. then in render properties, make sure to set the resolution to miniscule values, and in the Film dropdown set filter size to 0. that's the secret recipe