Not everything is done in Photoshop.
A dedicated 3D application is used on those images.
Choose an application. In this example Blender.
Learn how to sculpt what you need. In this case, I am downloading an already made hair and head.
- Adjust light and material. Render.
Now, on Ps
- Remove the unwanted background.
- Mask and compose.
I made a very lazy work. Making it right takes time. You need to understand how the 3D software works, some light and photography principles besides using masking and layers on Ps to compose it.
If the conditions of the face are suitable, you can play with it to make it look plastic or matt metalic. Things to consider when creating realistic highlights and dark reflections on metallic surfaces