Subject
To introduce shader lod, you need to read the official document first
The role of Shader LOD
Fine tune shader performance on different hardware
Instructions
1 Define multiple subshaders in the shader, and then set their lod values
2 The c# code sets the log of a certain shader, for example, Shader.maximumLOD = 200
3 The lod value of the front subshader should be larger
In this way, when running, unity will use the subshader of the specified lod to run the rendering.
Set the global shader Lod: Shader.globalMaximumLOD
Remark
The default Lod value of the new shader is -1
The default value of Shader.globalMaximumLOD is 2147483647
possible misunderstanding
Myth 1: The Lod of the shader is related to the camera distance.
Correct understanding: Shader's Lod provides an interface to choose which subshader to execute
References
ShaderLab: Specifying LOD values for sub-shaders - Unity Manual