In fact you can import a low poly model and use traditionnal subdivision tools and traditionnal sculpting ones (like Zbrush).
After that you can bake normal and paint on textures or 3D model.

For Voxels, you must start from voxels, than do retopo or import a low poly for retopo.

Well 3D Coat is so easy , and retopo so powerfull, it's very fast to do a hig model in Voxels , and retopology it.
Baking normal map is pressing one button in the proper menu.
After that you can paint freely on the 3D model or ot's textures.