I tried this, and it works on both the iPad and iPhone! Just printed an email to PDF and saved it to Dropbox! YAY!!!!
https://9to5mac.com/2016/06/16/ios-10-airprint-bluetooth-beacon-create-pdf-printing/
Create PDF
Also new in iOS 10, you’ll now be able to create a PDF from the print panel much like you have long been able to do on the Mac. After selecting Print, you can access the feature by pinching out from the print preview screen with two fingers and hitting the share menu in the upper right corner (or use peek and pop with 3D Touch instead of pinching). Any app that can accept PDF sharing will be under the share menu and you can send your newly created PDF from there.
https://9to5mac.com/2016/06/16/ios-10-airprint-bluetooth-beacon-create-pdf-printing/