Well, I have an idea of how to do it. I know that I need to find the geometry, skeleton, and IDs of the desired creatures, and then use Maya or 3ds Max to modify everything as I want. But after that, I don't know what to do).If I said something wrong, please correct me.
I have basic knowledge; I know how and where to get textures, animations, effects, etc., but modifying the model itself will be more difficult).
Then I'll write here what and how to do.