Just got a new phone (OnePlus Nord 3), turned refresh rate HUD in developer settings and I see some parts of the system and some apps display 120 Hz but I have problem noticing any difference, same with my wife’s Redmi Note 12, i have to look very carefully and maaaybe I notice some different, not sure
You’ll only really notice it when things are moving and only when it’s about 60+ frames per second. Otherwise, your display is just refreshing static objects more frequently. It will not have anything to do with quality of images. You might notice an increase in responsiveness since the screen refreshed sooner, but that is generally minimal.