>>2399148Aah, UV Mapping.
As far as I know, it's all hand made, depends on the complexity of the 3D model.
You need an image editing software when you are working on the textures..something like photoshop or gimp to paint the details on your model.
https://www.youtube.com/watch?v=f2-FfB9kRmEhttps://medium.com/@sdixon3/uv-mapping-texturing-and-shaders-rigging-and-animation-be9b4ddf0d48