Any number of docks exist which demultiplexes both DisplayPort signals from the Thunderbolt bus and also provides USB C ports some at 10gbps even but I can't find one that puts the DisplayPort signal into the USB C ports. In other words, instead (besides?) of DisplayPorts, provide two DisplayPort Alternate Mode capable USB C ports. This would be useful -- especially if portable -- to drive two USB C monitors from a single port on the laptop.
A more clunky solution would take power from USB A (even 5V 1.5 is enough, 5V 2.4A would be plenty) and a DisplayPort signal to provide a DisplayPort Alternate Mode capable USB C port. I've never seen such either.
Note this is not about getting the DisplayPort signal out of a USB C port, such adapters are ubiqutious and cheap.