Does macOS resolution setting affect watching 4k videos on a 27 inch iMac?

I always use a 2020 27' iMac (5k screen) in the mode of scaled resolution 2048\*1152 (<4k) with larger text so as not to exhaust my eyes. (System default is 2560\*1440, also <4k, and it can go up to 3200\*1800 with very tiny text.) But does this affect the quality of watching 4k videos? Can the screen smartly play videos at its full strength or not?