Transfer files between your iPhone and computer with an external storage device
Connect your iPhone or computer to an external storage device, such as a USB drive or SD card.
To connect to iPhone, you may need a cable adapter. See Connect external storage devices to iPhone.
The first time you connect the devices, select Trust when asked on iPhone whether to trust this computer. (See the Apple Support article About the ‘Trust This Computer’ alert.)
Use a supported app like Files or Pages to copy files to the storage device.
For example, to copy a file from the Files app on iPhone to the storage device, touch and hold the file, then tap Copy. Tap Browse at the bottom of the screen, then tap the name of the device (below locations). Select a location for the file, touch and hold the screen, then tap Paste. See Organize files and folders in Files on iPhone.
Disconnect the storage device.
Connect the storage device to your other device, then copy the files to that device.
For example, to copy a file to your Mac, click the Finder icon in the Dock to open a Finder window, select the storage device (listed below Locations in the Finder sidebar), navigate to the file, then drag it to a folder on your Mac. See Connect and use other storage devices with Mac in the macOS User Guide.