Iphone 13 add an email sound notification

It is the window you get when you connect your phone to your computer by USB. If the .m4r is in the desktop then simply drag it to the middle of the window. I know it works on Mac, I'm pretty sure it works on PC the same way.

I suggest doing a web search for iOS custom ringtones. Once you install a ringtone you can use it for any notification, including email.

You need to connect to a computer and establish a sync window then drag the file into the window.

The .m4r must be less than 30 seconds