By default, the textures have an LOD system, so when the mesh gets further away it will go to a lower resolution of the textures. For a mesh LOD what that would mean is that you’ve modeled the mesh again at a lower polygon count so that when it gets further away it will switch to that lower-resolution mesh as well as changing to lower-resolution textures. If you want to make a mesh LOD you will need to bake your textures for that yourself, most likely you’ll need to bake the normal map from your original high resolution mesh.
UE4 has an automatic tool for generating mesh LOD’s where it will also generate textures for it, but I don’t think that works for skeletal meshes.