Questions about the wetness effect about hdrp-custom-passes HOT 1 OPEN

So, right now this is not possible because it's a screen-space effect. Though with more work you could set up a volume system (like in your picture) that you pass to the shader to fade the effect.
You'd need to convert the list of volumes to a list of OBB with a fading radius and upload it with a GraphicsBuffer. Then in the shader, you can simply iterate over all the volumes to find the minimum fading value to apply at a certain position in world space.

An alternative solution to locally apply wetness like that is to use a decal shader graph: https://docs.unity3d.com/Packages/[email protected]/manual/master-stack-hdrp.html

from hdrp-custom-passes.