I cannot seem to find the way to alter the properties of a Physically Based Material created in Xcode.

For example, I have a material in Reality Composer Pro called Skin_Material

Now I can to alter the opacity property of the Skin_Material with a slider as shown below:

@State private var skinOpacity: Float = 0.0

Slider(value: $skinOpacity, in: (0.0)...(1.0))
    .onChange(of: skinOpacity) { _, _ in
        // What do I put here?
    }
}

I think I won’t be the first one to be clueless in this endeavour so any guidance would be great.

I know there is a resource from WWDC that does this with a ShaderGraphMaterial Here, but this is not applicable to altering physically based materials.