Hi Billyqb,
It appears you're wondering which exact cords or adapters that are needed to connect your iPad Air (4th generation) and a USB drive. Check out the helpful information below, from this article: Connect external storage devices to iPad - Apple Support
"Depending on your iPad model and external device, you may need the Lightning to USB Camera Adapter, Lightning to USB 3 Camera Adapter, USB-C to SD Card Camera Reader, or Lightning to SD Card Camera Reader (all sold separately).
Note: A USB drive must have only a single data partition, and it must be formatted as FAT, FAT32, exFAT (FAT64), or APFS. To change the formatting of a USB drive, use a Mac or PC."
This article might also be helpful: Using USB accessories with iOS and iPadOS - Apple Support
For the iPad Air (4th generation), you would need an adapter that has one USB-C end to plug into your iPad Air and then the applicable end needed for your USB drive (or any other devices you may want to connect). You'll also want to pay special attention to the Note part from the article above. If the formatting is not right, you won't be able to view the contents on a USB drive.
Best wishes to you.