What phones are you talking about here? Are you asking about the ring the other person hears or the one you hear when someone calls? What is your ultimate goal with this "project"?
When I changed phones (2013 Moto X to Nexus 6P), I was able to browse to the file using a file manager (Solid Explorer is now my go-to, free for 14 days) then "share" the file using Beam and transfer using NFC. The sounds are in /Notifications or /Ringtones and named the same as they are on the screen when in the settings.