I can’t seem to find the Sprites-Default shader source on my Assets or Packages list. Do I have to modify the shader script itself manually? I am not familiar with how to find and edit these preset shaders, so I could use a step-by-step answer, if possible.
If you wish to modify the internal shaders, you can download a copy of the source files here;
Just find your version of Unity and then select “Built In Shaders” from the dropdown.
However, GPU instancing is already a part of all main included shaders in Unity (including sprite shaders), so you shouldn’t need to modify the shader at all. If you wish to enable GPU instancing on a material, there is a checkbox underneath the main material properties;