Fortunately, Apple thought of this and added two easy ways to get to your recently used files. The first is with Quick Actions. Long-press the Files app on your home screen and you'll see the last four newly opened files in a popup — just tap one and you're on your way!
Alternatively, you can add a widget to the Today view, which will provide the same information with just a swipe to the right on the home screen. This method is especially helpful if you've hidden the Files app in a folder, or have a ton of apps on your iPhone.
Just updated your iPhone? See everything that's new with Apple's latest iOS update: