For non-subscription options, some people download audio from YouTube using online converters. You paste the link, choose MP3, and download. It works, but you have to be careful with sketchy sites.
Yeah, and keep in mind that download audio from YouTube methods outside official apps can violate YouTube’s terms, especially for copyrighted content. I usually stick to creator-approved or my own uploads.
I mostly use it for lectures and public-domain stuff. As long as you’re mindful, there are plenty of ways to download audio from YouTube depending on what device you’re on.