You can with a lightning USB drive or a lightning to USB adapter, but it'll only transfer at USB 2.0 speeds on most iPhones, iPads, and iPad Pros with Lightning. Some will apparently do USB3 speeds but you need the right adapter. And if you plug it into your iDevice into your computer with a lighting to USBC or A adapter, it's still just USB 2 speeds. At least as of the last time I looking into it. Apple always made it hard to figure this out. The newer USB-C ones you can transfer faster.