This thread was helpful for me HDRP 2021.2 Grass Texture? . Grass textures seem to have been dropped (?). You now have to use meshes (?). But here is an example of a project that I just upgraded to HDRP. There is a house that is gone, some of the grass is now white rectangles (the rest is gone), the lake is gone, the road is gone, all the trees are gone (this was a house in the forest). I can probably get most of it back messing around with textures, but it certainly is not an clean process upgrading to HDRP. (This was the result after applying the HDRP wizard.) Too many custom shaders you have to hand update.
