USB-3 speeds are up to 10 Gbps slightly above your local Wi-Fi from your router's speed. The latest iPhones are only USC-C connections. Thunderbolt is a Mac additional feature. For Thunderbolt speeds you need a Thunderbolt port on both sides of your connection.the ports dont do thunderbolt but a lot of USB-C cables only do usb 2.0 transfer speeds so by using a thunderbolt 3 cable which uses the USB-C connector your going to get at least USB 3.0 speeds.
Dave