There’s a short hard-wired cable terminating inside of a USB Type-C plug, and all this from a device no larger than some typical card readers. Ahead of paying for an iPhone SD card reader, it’s necessary to know which devices are appropriate. Here's the iPhone products that support SD card https://microsdcardreader55320.gynoblog.com/26123183/multi-memory-card-reader-usb-fundamentals-explained