How do i set an mp3 as my ringtone iphone 7 IOS 15.8.1

[IR76]

I have the mp3 file in my files but garageband needs IOS 17 or later and thats not possible on the iphone 7. 

[WhitetailAni]

Convert them to m4a files and add them to the Tones tab in iTunes. You need iTunes specifically - if you're running Catalina-Ventura, you can use https://github.com/cormiertyshawn895/Retroactive.

If you're on Sonoma, it won't work.