DVD is A storage system.
It just so happens to be used mainly for videos
Dvds can have videos in 4k on em.
Dvds also store music, operating systems and anything else you want.
Yes, DVDs can be used to store data, and as such HD etc. video files. (Which a DVD player may or may not be able to play, given the multitude of different video codecs.)
But this was about commercial DVD video disks, and the original DVD video standard is SD, 480p. If you rent or buy a film on DVD it will be 480p.
https://en.m.wikipedia.org/wiki/DVD-Video
Towards the bottom HD DVD is mentioned, but as you can see that attempt was quickly aborted.
Good luck getting more than 10 minutes of 4K video on a DVD.