So the answer is not that straightforward. Bottom line 4:4:4 is a colour encoding scheme that takes a lot of bandwidth and is really only noticeable with text and graphic type images, hence the need for it on PC monitors. The bandwidth requirements for 4k hdr are too high for it on HDMI 2.0, so 4:2:2 is used instead. LG has implemented 4:4:4 but you need to set your input icon to the PC. Press the input button on your tv, go to all inputs, and change input icon. This has the added benefit of getting low (21ms) input lag. The expense is the lack of image processing, and supposedly incorrect mapping of colours in HDR.
In your case you are using only one input on the TV, so I wouldnt recommend setting your input icon to PC, because even for movies youll lack image processing, and will not have correct tone mapping for 4k hdr content. Instead Id switch back and forth between game mode. Alternately you can switch the icon to PC when playing SDR games, and for HDR games switch back to a different icon and go to game mode.
I have a two output receiver so I set up my harmony remote to switch inputs on the tv depending on whether Im SDR gaming , HDR gaming, or movie/tv watching. Its kinda a bitch but using an AVR with 8 inputs is my only option if I want lossless audio and all my devices connected (x1,ps4,switch,cable box, htpc, uhd bluray player, Apple TV 4k).