Brute Force - Grass Shader Documentation
6. Mac & Mobile Shader
You will quickly see that the Mac & Mobile shader have some properties missing in the materials and that you cannot tweak the grass layers, moreover if you drag and drop a Mac & Mobile material on a simple geometry this is what you'll get:
And it's because you need a custom script to make it work properly on Metal rendering devices, if you take a look at the 02GrassSetupMacMobile prefab:
"BF_MeshExtrusion.cs" script is the main difference between the normal shaders and this one, it will create extruded layers of an original mesh and output it in the mesh filter property of the asset in editmode and realtime.
It is recommended to not go beyond 17 number of stacks as it may reduce performance.
There is a full Mac & Mobile scene "02MacMobileShowcase" that I strongly recommend you to look at when building on Metal: