Lights and shadows in a custom unlit shader in BIRP

Hey guys, I was following along with this tutorial, Custom lighting in Shader Graph: Expanding your graphs in 2019, on how to add lighting in shader graph. I got the surface lighting to work but I’m not sure how he is doing the shadows. Does anyone know of some tutorials like that? I am using an unlit shader on the built in render pipeline.

Or if that’s not possible then is there a way to use a lit shader but be able to edit the final color after the lighting stuff is done?

I want there to be no lights at all, completely black, when you go underground where there is no light.

But I want to be able to change the colors still.