Do G-Sync and FreeSync work over USB-C? Yes, but it's complicated
Adaptive sync technologies like Nvidia's G-Sync and AMD's FreeSync work over USB-C, but you need to make sure your hardware has all the right capabilities.
Lenovo Thinkpad Intel Graphics Command Center Displayport Alternate Adaptive Sync Displayport Alternate Mode Nvidiag Sync
Source: pcworld.com