If you are going to Animate a Sculpt, you’ll have to re-Topologize and then you can Assign different Materials to different parts of the Mesh.
You can also Paint in Sculpt Mode.
If you have used Multires, or have a Low Poly version of your Model, you can Bake a Displacement Map, which you can use to ‘separate’ parts based on their ‘elevation’ from the Low Poly version.
