It depends how big the screen you have is.
Once you start to hit 65" to 96" 4k will help a lot to maintain detail at larger screen sizes.
HD would still be acceptable but really the larger you go you really neeed to maintain resolution comparable to size of the screen surface.
Generally people don’t have space for such large screens in their homes whilst 4k can still be enjoyable on lower size screens essentially 4k is negligable or won’t provide anything worthwhile probably under 40" screen size.
Based on being a reasonable / normal viewing distance from the screen display.