There’s multiple tricks to reduce aliasing, the shader one probably hasn’t been implemented in UE4, but the Normal To Roughness has. Basically all you need to do is have a normal map and a roughness map, and UE4 will automatically generate the mip-maps for both to reduce specular aliasing when viewed from a far distance and/or if the normal map has very sharp or bumpy details. It’s kinda like precomputed anti-aliasing that maintains correct roughness.