how to combine materials into one within unreal ?

Hello there ,I have a question. There are some characters mesh with more then one material, like the sparrow character on unreal market place . And I don’t know any DDCs , so I am wandering is there any way to merge them to one? The way like merge static meshes into one mesh, then it comes with a single material that suits the mesh. Where is the merge material button work for skeletal mesh, is there one?