how preview the wrinkles in unity

[koffertje]

hello there,
i was wondering if there is a option to preview the wrinkle maps in unity on the 3D model.
there is not much documentation about these wrinkle maps in unity.
we know it is there but i don't know how to use it.
when im in playmode and i change blendshapes values for example the eyebrows. the wrinkles maps won't work, they don't seem to blend.
i tried it in urp and hdrp

would be nice if there is some more info on this.