Things may have changed since then, but when I first encountered the project several years ago it seemed like the thing that made this project stand out compared to other player projects was a big emphasis on correctness and accurate playback. There have files I’ve encountered that for example VLC will play with quirks (color reproduction is not quite right, etc) that mpv plays perfectly.
no-config
target-trc=pq
target-prim=bt.2020
vo=gpu-next
BT.2020 are the primaries used to encode the HDR movie.
Monitors with such primaries are rare and extremely expensive. For most good monitors "--target-prim=dci-p3" should be appropriate, if DCI-P3 has already been selected from the on-screen monitor configuration menu, because most monitors come configured by default to use the ugly sRGB color space, so you must change the defaults to be able to display content with bigger color spaces.
Some monitors might have the option to use the BT.2020 color space, when they would still not be able to display all of it, but they would do internally the conversion between the BT.2020 used to encode the movie and whatever color space the monitor can actually display.