As far as I know, the PS4 does not have a display port. It is possible to connect the PS4 via HDMI cable (a normal one) but then the monitor frequency at 4K would only be 30Hz and that is unplayable.

why would you need a DP? it does have HDMI inputs? or am I wrong?

Ps. The ps4 cannot display content in 4k at all

As if that would be unplayable! It is possible to connect the PS4 via a Displayport, but then you would need an HDMI to DP adapter and that would be unnecessary. And I wouldn't use a 4K monitor -> 1080p or 1440 with 60 FPS.