The amount of time it takes you to type that ask is probably the same amount of time it takes for you to learn toning.
Because it’s really pretty simple.
First you make two layers on Photoshop. I called them lineart and tones
Then you draw whatever you want on the ‘lineart’ layer. Let’s say this dude.
Go to the color thing and pick a gray. Any gray. I like to start with light one, maybe 90% on B (brightness)
Then I start slapping some of that gray on the ‘tones’ layer.
Add more grays with different values. Here I added 70% and 50% B
Yes, it’s messy, but the tones and the lineart are on different layers, so you can just erase the mess on the tones without affecting the lineart.
Play with some colors and VOILA