Change Job Type to FAX, don't go into Fax settings. I can't supply screenshots as I don't have a Mac to do it on.
In the last screenshot, change Safari to Xerox Features and you will be able to change the Job Type from Normal to Fax
Previously I was able to PRINT TO FAX
In the printer dialogue, there used to be an option to enter a Fax number. It seems to have disappeard, Not sure when, cause I dont fax often.
Mac 10.14.6 Mojave
WorkCentre 6505DN LAN Fax v1.8
Few Screen Shots of the Printer Dialog Box and Setting Box