How to create a custom iPhone ringtone using MacOS 10.15 Catalina? How can I create and upload a custom iPhone ringtone using MacOS 10.15 Catalina?

I have tried to follow the advice given for uploading ringtones applicable to older versions of MacOS, where iTunes was available, substituting the replacement Music program instead, but I don't seem to be able to drag or open the .m4r file that I have created into Music, nor drag it onto my iPhone in the Finder.

Is there still some way to convert other audio files into ringtones and upload them to iPhones when using MacOS 10.15 Catalina?
'Create ringtone' part for Catalina (and older macos versions as well) is pretty simple and straightforward if you are comfortable with terminal. 

MacOs comes with built-in afconvert. For example, to convert mp3 file 'mysound.mp3' to ringtone (.m4r file) mysoundringtone.m4r:

afconvert -f m4af -d aac mysound.mp3 mysoundringtone.m4r


Need to be in same directory with source file or pass path along with filename(s).

'Upload part': one can connect iPhone to computer and drag-and-drop ringtone file to iTunes while it's on iPhone 'General' tab. After that locate newly created ringtone on iPhone in Settings > Sounds &amp; Haptics > Ringtone (above built-in ringtones, separated by line).