Save audio from a myvideo to import as music

Just trying to extract the audio from video A, save it in a useful format like mp3, so I can import it as audio in the future. I can do this on some social platforms mobile apps, but I'm sick of having to do it seperately for each company. With YouTube I've been getting by with the screen recorder on the iPhone to record my own shorts and videos I've uploaded to it.

Thsnks for your patience