how can I convert video to audio on iOs

Hey sabrina, here’s a website you can use.
https://audio.online-convert.com/convert-to-mp3
This should still work, even though it says convert audio. I use this website for all my converting. You can convert any video. You can just paste the link in the edit box or you can choose a file from your photo library. This website is pretty accessible, in my experience. Now if you’re trying to convert a YouTube video to audio then use this link
https://www.onlinevideoconverter.com/mp3-converter
Just paste the link in the edit box and click go. I use this when I am going to go somewhere with no Internet connection. Since I don’t need to see it lol. Audio is perfectly fine.
Let me know if you need any help.

Oh and I forgot to mention in my previous post. You might need an app with a download manager. Here’s the app that I use.
https://apps.apple.com/us/app/browser-offline-file-storage/id970487401
Now that I think about it, you might have to copy the link of the website I provided and paste it into the browser of the app.
Hth

I have been using this app for all kinds of conversions, including video to audio. But for some reason the app is not to be found in Appstore. Do check if it's available in your region.

Hth

What I am wanting to do is convert a YouTube video that I did not upload to an audio file, and I’m also wanting to edit it.

Basically all I’m wanting to do is add the speed on it.
But generally what I need to do first is find an app or something to where I can convert a downloaded YouTube video to MP3.

Is there a way that I can do that?

I don't know about converting a video from somewhere online, but if you're just wanting to convert a video you make on your iPhone, no need for a separate app. After some googling I made a Siri shortcut to convert a video from my camera roll to audio since for some reason Apple doesn't allow stereo audio recording except in videos.

It works great! My convert video to audio shortcut converts the video to an AAC file and saves it to iCloud Drive. It shows up right on the share sheet for the video in my photos app, or I can ask Siri to do it.