This app was mentioned in 4 comments, with an average of 0.75 upvotes
There's apps out there that allow you to send PDF files. Check out Fax File
Android app: https://play.google.com/store/apps/details?id=com.actualsoftware.faxfile&hl=en
IOS app: https://itunes.apple.com/us/app/faxfile-send-fax-from-iphone/id672100118?mt=8
I mean... technically it does...
I've used Faxfile successfully before: https://play.google.com/store/apps/details?id=com.actualsoftware.faxfile
It certainly is capable, and if you haven't found any apps You aren't really trying very hard
This is literally the first thing to come up when I typed in "Google play fax"
Very few people want to send faxes from their phone as hardly anybody does much document manipulation there, but if you want to you can.