Most of those files aren't even pushing 20 GB. They're heavily compressed 4k video files. I'd choose 1080p at that file size as the video bitrate would be substantially better.

Resolution isn't everything in video, if you have to sacrifice a high bit rate to achieve a low file size at a high resolution then the quality is in fact, worse.

A good 1080p video is usually about 15 GB. If you want a true quality 4k file, then the file size is about 50 GB. Even then, they're compressed too. A true 1080p video is about 40 GB, if not substantially more.

A true 4k video with slight compression is pushing 100 GB.

Download a 1080p video at that file size, you'll notice a huge improvement in picture quality, honestly.