Where does my information go when I save a PDF file
Where do my saved PDF files go when I save them
iPhone 7, iOS 12
It depends on the apps that you have also on the app that you have selected while saving. If you didn't get the selection option that indicates you either have only one app which can store PDF files. That may even be Files App.
When you AirDrop there is an immediate popup to Accept (In case of another Apple ID) and then where to store (For all Apple IDs). Watch the GIF below