Apple makes it hard to not use iCloud, at least for a few things. Since their cloud storage is baked so deeply into iOS, using iTunes on the desktop to manually move files and backup your device can sometimes feel like an awkward step backwards. To give your iPhone more flexibility to manage large files and get some much-needed expandable storage, take a look at the iKlips miReader 4K.
This mobile external drive connects to the lightning port to give your device up to 256GB of extra space via microSD card. It bypasses your phone's internal storage when it's plugged in, so you can shoot 4K video and transfer it directly to the miReader without using any phone storage. Plus it accepts files from any other microSD device, so you can use it as a portable backup for other cameras as well.
You can quickly move files between all of your devices without an internet connection or cloud storage subscription with the iKlips miReader 4K. Pick one up in the Boing Boing store for $46.99.