First of all, sorry for my English, it’s not very good.
1.- I duplicate the layer of the lineart and change the color to a purple.
2.- I reduce the opacity (30% opacity).
3.- I duplicate this layer one more time, I apply the Gaussian blur filter (20%) and use the Burn blending mode (35% opacity).
4.- I duplicate this layer one last time (the one with the Gaussian blur filter) and use the Geometric Mean blending mode with 100 percent opacity
5.- Group the layers and activate “pass through mode” :
These are a few “tricks” I learned from analyzing Ilya’s work and trying to replicate the effects he uses in his illustrations.
I hope my explanation is understandable