New Storage Options with the iPhone in iOS 11
Think of the iPhone Storage setting as one of the places to go on the iPhone for statistics about how you employ the device. You find other information in the About setting (under General on the Settings screen). A list of all the apps taking space on your iPhone appears.
Ask yourself if you really need all the apps that are hogging the most space. If not, tap the name of the app and then tap Delete App. (You can’t delete a native iPhone app such as Safari or Mail, not that you’d want to.)
Through iOS 11, you can offload an app without deleting it. Choosing this option frees up bloat but also keeps the documents and data associated with that app on your phone. As long as the app is reinstalled (and assuming the app itself is still available in the App Store), the documents and data will again be available to you.
Another new option available through iOS 11 lets you automatically delete older conversations in Messages. Older in this context is defined as conversations received one year ago or longer. When you enable this option, the setting is ongoing.