I've got a 55" LG oled & I have to say that 4k is the least impressive feature on it. If you put a gun to my head I can maybe tell the difference when netflix is displaying in 4k over 1080p but imo it's more marketing than material difference at this point. To really feel a tangible benefit you really need to be sitting close by & go for 65" plus.
The fact that you need a GPU 4x the power to play the same game at 4k over full HD, which for most people will result in a subtle improvement, if any at all, makes the whole thing a bit of a false dawn!
That extra power could be used for so much - it's a shame that Sony & Microsoft's hubris is finding it's target...