As spotted by Cydia Geeks, iOS 11 introduces a new storage-management option called Offload App. This will free up storage used by the app, but keep its documents and data. Reinstalling the app will place back your data if the app is still available in the App Store.
There’s also a second option to allow your device to automatically remove rarely-used apps when you run low on storage. This option is found in General > iPhone Storage. With this enabled, your settings and data will be automatically saved, but the downside is that you may unexpectedly find an app you want to use isn’t available without downloading it again.