Music running app?

Hello folks! 🙂

I want to create a long audio, like a song, just it’s not a song, but many different noises that I cut together,

Now I would like to let it run overnight, but my cell phone should be switched off if possible, so it’s like playing music but you have your cell phone off and it doesn’t have to stay on this app all the time so that this music can be played also keeps running.

I have an IPhone, and now my question is if there is an app where I can upload this file and play it overnight, but my phone doesn’t have to be on, it has to stay on the app?