best video, best audio, MKV remux:

yt-dlp -f ba+bv --merge-output-format link

best video UNDER 1080p, best audio, MKV remux:

yt-dlp -f "ba+bv*[height<=1080p]" --merge-output-format mkv link

output name:

yt-dlp -o name.mp4 link

video to mp3:

yt-dlp -x --audio-format mp3 -f bestaudio link