It is not possible in IOS Safari to print to PDF or save to PDF without using a 3rd party app, such as Save2PDF. (Which I personally use quite a bit with good success.) On my local network I’ve used Printopia for years and print pages from iPad or iPhone to DEVONthink on the desktop. It is possible also to use apps such as Save2PDF to make a pdf, send it to DEVONthink to Go for syncing to the desktop DEVONthink. I believe other iOS browsers (Dolphin?) have plugins for PDF capture.