What do i need for full potential?

Hey Guys!! Usually i don't post stuff on reddit but i need a little help.

I got a 4k 144hz monitor a while back as a present. I play on a Ps5 slim and most of the time i play single player games and occasionally online games.

Now, i play Rdr2 a lot and also rdo, i noticed that my graphics are still a bit blurry which bothers me slightly.

I tried to research a little, do i need a hdmi 2.1 for full 4k experience? Is it my settings? Or is it something else?

Any help would be appreciated!!