Curtis Holt release a free Material pack community package that includes a blend file containing a variety of useful materials for Blender.
You can Add this file to one of your asset library folders to be able to drag them into your blend scenes using the asset browser. Check (Edit - Preferences - File Paths) to create and manage new asset libraries.
You can also append the materials from the file directly by using File - Append.
You can easily download the free material pack community by choose the third version update (v3.0) that add new materials and bug fixes:
https://curtisjamesholt.gumroad.com/l...