Get a flash drive, get the Lightning to USB-A adapter from Apple, get a USB-C to USB-A adapter, format the flash drive as HFS+ on the Mac, and have at.
Connect external storage devices to iPad - Apple Support
This’d all be easier with a newer iPad with USB-C, as there are USB-C flash drives, and a recent Mac will have USB-C ports. No adapters needed.
Or use AirDrop, which uses ad-hoc and doesn’t need an associated Wi-Fi network.
How to use AirDrop on your iPhone or iPad - Apple Support
Use AirDrop on your Mac - Apple Support
If a connected Wi-Fi network becomes an option, the available options increases.