Question Shader in built in render pipeline

Hi Everyone,

I want to create a shader for a mobile game ( built-in render pipeline ) which will have

Channel 1 - color map ( 128 resolution)
Channel 2 - light map (1024 resolution)

Where can I find this in unity ? Please help

 

The easiest way would probably to use Shadergraph
https://docs.unity3d.com/Manual/shader-graph.html

Or by coding a surface shader
https://docs.unity3d.com/Manual/SL-SurfaceShaders.html
Particularly, there is an example of using a custom lighting formula.
https://docs.unity3d.com/Manual/SL-SurfaceShaderLightingExamples.html