This is a paid asset, but now you can download Volumetric Clouds for FREE, Please keep in mind this package is provided only for learning purposes or to be able to test before buying the product, NOT FOR COMMERCIAL PURPOSES.
For more detail this asset from the Unity Asset Store: Click Here
Volumetric Clouds v3.5 (Latest version)
“If possible, please buy the package to support the developer”
Volumetric Clouds is a fullscreen shader which uses raymarching through a texture to render fully 3D clouds on screen.
This package contains the following :
-A shader and a cginc file
-A C# script to attach to a camera and another one to fire events linked to clouds
-Two materials, acting as presets for low and high quality
-A bunch of editor scripts for the material inspector
-An offline manual
-Four texture variant
HDRP & LDRP not supported yet.
Video
Online Manual
Forum Thread