I've been using a 55CX for 2 months now and loving it. I sit in an armchair at approx 5 feet away, display is used for a mix of desktop work, gaming and movies (physical media, no streaming). Not worried about burn in as I've upgraded from a 2011 panasonic plasma (1080p60 8bit 4:2:2) of equal size and they were worse for burn-in but by learning good habits and many UI tweaks I avoided permanent burn in so an OLED should be no trouble especially with the ASBL function. GPU is a 3080Ti. Before various plasma TVs I was still using CRT monitors (1600x1200 at 75Hz) as I've never liked LCD or LED.
For desktop work (i.e. web browsing, MSoffice work, video conferencing etc) the output is 3840x2160 120hz 10bit 4:4:4 RGB Dynamic Range=Full, windows HDR=off, windows DPI scaling at 200%. No crushed blacks or whites, colours look great. The upgrade to 4:4:4 capability (plasma could only do 4:2:2) is very nice indeed.
For gaming I don't bother with the VRR, instead I adjust the game settings to get constant 120fps. In older games 3840x2160 120hz works fine at highest/ultra settings. In games from the last couple years I either have to compromise on graphics settings or resolution, and I prefer to decrease the resolution to 2560x1440 120Hz* or use DLSS if available and keep most of the settings on highest/ultra and maintain solid 120fps. Looks fantastic. Playing RDR2 right now and it's really spectacular, even in SDR.
*Even though the CX supports it, some games won't let me select 2560x1440 120Hz, but they will allow 2560x1440 at 119Hz, looks the same but just odd.
Majority of my movies are HD Blurays or DVDs, no UHD or HDR yet. MPC-HC + MadVR does a great job of upscaling to 4K but it does push the GPU somewhat and get the fans going.
Can strongly recommend LG CX/C1 OLEDs to anyone considering it for a gaming monitor, if you can manage the size.