The default printer port for Microsoft Print to PDF printer and Microsoft XPS Document Writer is 'PORTPROMPT:', which falls into the 'Local Port' category. On Windows 7, the port is named 'XPSPort:' for Microsoft XPS Document Writer, however, on Windows 10, it comes with a new name 'PORTPROMPT:'.
Microsoft Print to PDF printer uses the same document graphics pipeline as Microsoft XPS Document Writer.
To fix your problem with Microsoft Print to PDF printer, I would suggest you to download a free software program called 'Repair Tool for Microsoft Print to PDF' from,
https://www.windows10pdf.com/print-to-pdf.html
Click 'Clear Print Queue' button to clear the print queue, and then click 'Reinstall Printer' button to reinstall Microsoft Print to PDF printer. After you complete the steps, Microsoft Print to PDF printer is reinstalled and the default settings for the printer are applied, as well as 'PORTPROMPT:' port is reassigned to Microsoft Print to PDF printer. Your problem can be resolved.
If you are looking for PDF Options, simply click 'PDF Options' button to load the PDF options dialog. There, you could change page orientation from portrait to landscape, and change paper type from Letter to other types, for example, A4.
If you would like to bypass the 'Save Output As PDF' dialog, you need a more advanced tool to automatically and/or programmatically save PDF files without prompt. This kind of automation tools are many, however, none of them is free on Windows 10.
A less expensive one is Print to PDF Toolkit Pro, which can be regarded as Microsoft Print to PDF Pro version. I do not like to introduce paid software, if you would like to try Print to PDF Toolkit Pro, just go to the same website as the Repair Tool for Microsoft Print to PDF.
Enjoy!