Yes. I just tried it. Press and hold the attached mp3 file and select Save to Files. I put it in my iCloud Drive > Documents folder. Then I open Files, navigate to that folder and play the file.
Yes. I just tried it. Press and hold the attached mp3 file and select Save to Files. I put it in my iCloud Drive > Documents folder. Then I open Files, navigate to that folder and play the file.
You can import and play .mp3 files on your iPhone, but not store them in the Music app. There's several apps that will allow you to store & play any music file.
You need a separate music player that supports local storage for that to happen. Stock music app won’t allow user to put anything into it without iTunes or iTunes Store or Apple Music.