Canon DSLR cameras can have their focus controlled via the USB interface and the EOS Utility provided by Canon. Devices were created by several manufacturers to simulate this interface via USB to control a Canon camera's focus, recording and other settings. Up until the 5D Mark IV the USB interface was the same and consisted of a USB 2.0 plug on the camera.
With the 5D Mark IV Canon has upgraded to USB 3. I have confirmed that these devices do in fact work with the 5D Mark IV just as they have with the previous bodies.
USB Follow Focus devices include the Okii Follow Focus Okii Systems FC1 USB Focus Controller and the Manfrotto MVR911ECCN . I was able to control the 5D MK IV with both of these devices. For the Manfrotto you will need to buy one of these USB A to mini-B 5pin and one of these USB 2.0 A Female to A Female Coupler Adapter
While the 5D Mark IV has superb AF, being able to control it manually may still be desired as well as being able to start/stop video recording. These devices work great when attached to stabilization devices such as the Movi.