With drag and drop iOS 11 became a lot easier to use for many tasks on iPad. Yoink is an app that improves drag and drop further.
Yoink is like a shelf to put things you want to copy between apps or just keep close at hand. There are other apps that do similar things, but at the moment Yoink is my number one choice. There is a Mac app as well and I have been using it for years.