I imported a model from blender, now I want to change it’s texture with a texture from a similar model.
This doesn’t work because the uv’s are different.
So what I am trying to do now is import the geometry from the second model and assign it’s uvs to the first model but the model remains black.
Those models look similar to the eye but their underlying data is completely different. Try opening the two textures side by side in an image viewer to see how different they are.
Your geometries are different so you can’t just copy UV from one to another, there is no real solution here except reworking the material of your new model.
If you just want to change the color of the jacket, just open the base color texture in any image editor and change the hue.