Hi-res audio and video are a definite step up.
Video is pretty easy to tell, if you have a big 4K TV and you sit close enough. In 2020 though, it's extremely common for people to have 4K 65" TVs. You don't even need a top tier 4K TV to be able to tell the difference. However, other things that are not visible on other TVs are often obviously improved on TVs like my OLED. I have a 65" LG C9 OLED, and sit 7-8 feet away.
For audio, you need a very decent audio system to notice a significant difference, which unfortunately most people don't have. I have a full Paradigm Reference Studio setup across the front for my mains (Studio 60) and centre (Studio CC), with Paradigm Titans in the back and Paradigm Atoms overhead for Atmos (Atoms for Atmos!), along with an SVS PB13-Ultra subwoofer. Unfortunately, since my home theatre is below my daughter's room, I now rarely watch in full Dolby Atmos glory, and just watching via stereo headphones.