Yes, NVIDIA is working towards certifying USB-C adapters from several manufacturers on Turing products. Certified adapters will be available in early 2019.
In the meantime, customers can buy the below adapters that NVIDIA has tested for high-level basic functionality with GeForce RTX graphics cards.* Please note that these adapters have not yet completed NVIDIA's robust certification process, but have passed basic functional testing.
*Note that while NVIDIA has performed basic functional testing, we cannot guarantee the compatibility of these adapters.