Hdri cube 4k*4k*4k*4k*4k*4k

I’ve noticed that 2k “cubes” are the maximum resolution unreal5 supports but if you have a 4k monitor and are using 90 fov that’s not enough you need 4k for the maximum screen width.
so I thought why not just use a 6 4k+4k and plot them onto a cube. but it does seem strange that ue5 doesn’t have an answer for this. but maybe I’m wrong am I?