I don't use Procreate myself, but Sugimori's style is typically identified by its watercolor-appearance, even when he moved to digital! When drawing traditionally, I've found that his lineart can be easily emulated with a brush-pen.
You could perhaps look up free watercolor brushes for Procreate, or mess with the settings that would allow the brush's edge to be "textured" or feel "random". The 4th brush in
Nadiaxel's free set seems like it might be helpful!
Hopefully someone with more Procreate knowledge could help you out, though!