I've noticed that media files seem to look "good enough" at 720p for cartoons and 1080p for live action. I know some people obsess over the highest quality of everything (4k 10bit HDR) but even those came out in 2016[1] and aren't that popular. Higher definition like 8k is basically non existent, it can't run on old HDMI cables and needs both a beefy decoder (Blasting heat) and a powerful display driver as well.
[1] https://en.wikipedia.org/wiki/Ultra_HD_Blu-ray