There isn't much to this except I was testing a couple things with layer modes in Clip Studio Paint. Back when I was in art school, I was taught the theory of how to do a painting over an underpainting. I never really mastered it then but I always thought it was a useful an interesting way to work. I'm less good at it digitally. But that didn't stop me from spending years trying to make this process work, and seeing if it could be a solid shortcut if I used Layer Modes.
The trouble is, the layer mode colors are never quite as effective as you would like. By the time you've fixed what layer modes couldn't do, you'd have had saved more time just painting it normally. Layer Modes are a useful tool but they don't completely supplant coloring basics.