Audio files on iPhones

I have an iPhone. Someone has sent me an email containing either an attached .mp3 file or a link to download an .mp3 files. In both cases, if I click on the file in the iPhone mail app, the little audio player pops up, and I can listen to the file. However, what I want to do is actually add this song to my music library on the phone so it’s playable at all times, I can add it to a playlist, etc. Can I do that without access to a PC running iTunes?
thanks

No

I don’t know but I suspect the answer is no. iOS generally doesn’t let you manage your media on your device. Android lets you do whatever you want.

I have read that on iOS some people use alternative music players that allow more flexibility in managing music files on your device.