A lot of people ask me how to get more storage space on their iOS device. You can’t expand storage on the device itself, but you can link to external storage with iOS13.
If you have an NAS drive connected to your router, then the Files app can link to it just as simply as you can link to Dropbox or iCloud without the bottleneck of the internet.
In the Files app, click browse and then tap the three dots at the top. Now ‘connect to server’ and enter the IP address or name of the NAS unit (e.g. ‘mycloud’). Once it has found the NAS, enter your user name and password if required.
Now you can move items from the iPhone/iPad to the NAS and have them at your fingertips whenever you are on your home network.