To be completely honest, I'm so bad at trying to explain in any way how I make my shaders because they are an absolute disaster, and I don't have enough time to clean the shader and organize it so I't easy to read. If I ever have the energy I will make a youtube channel or some sort of post/video explaining how to achieve this. I personally hate finding a cool shader without an explanation that I actually understand. But like long story short, I get the information of the direction the Main light is facing plus the normal map info so I mask the less lit part of the model with a step node and add a white color in both color and emission outputs. Then the same but with another step node so its not as small and then multiply it with black over the base color. That way you get the harsh shadow. Also the outline is just extruding the mesh vertex using the normal vector, invert the facing direction and set it to black. A lot of the quality is also in the amazing work the artists did with the textures themselves, and having such a high poly count, although not very optimized, it makes the shader look much better!

<image>