>>333831685
I'm assuming that you can actually transfer the clothing over in Unity, normally this requires Blender or JP autism. This is a two stage problem. To get the files in the same project, you can either copy over the scene AND all other bits you need in the other scene, or you can make a prefab of the avatar you want to copy over and export a package that you import in the other project.
After that, I recommend using Pumpkin's avatar tools to transfer over the transforms, dynbones, etc.