It will default to English, but you can specify another language with the flag –sub-lang:
youtube-dl –sub-lang sv –write-auto-sub
You can list all available subtitles with:
It’s also possible to skip the video and only download the subtitle if you add the flag –skip-download:
yt-dlp –sub-lang sv –write-auto-sub –skip-download
yt-dlp for some additional features and workarounds.
It uses the same flags as yt-dlp.