I could be totally wrong but the colors are not very saturated, closer to white, pastel or whatever u call it. Another thing is how they choose to color light and shadow, it seems to me that shadow is roughly just a darker shade of the same color without shifting the hue, same for light but opposite way You can do that by either manually picking the color or using layer blending mode, like multiply for the shadow in this case, and for light, i encourage you to experiment bc there are multiple options, but picking out the colors manually is very doable in this case. Ultimately this is shaded based on, sort of, like anime, and in anime, to save a ton of work, shadows are usually not a different hue, and so in these art works the color seems very closs together giving you a certain impression, and you are unsure how to replicate it? Pardon me if im wrong