/ic/ - Artwork/Critique

how do you render without needing to have lineart as fart of the final piece? pic related is what i'm trying to emulate. what i struggle with specifically is how the fuck to make clean shapes with colors alone. what i have always done until now is sketch > lineart > scribble in the colors while making sure they don't stray outside the lines, but i want to be able to do something like this.