Extension cord or "hub" for USB-C / Thunderbolt 3
USB-C and Thunderbolt 3 are different protocol in a same physical connector.

For a USB-C hub you can't support both DP(4K 60Hz) and USB 3.0.

A Thunderbolt 3 Hub will be far more expensive than a USB-C Hub. Unless you are ready to pay for it, it might be better to stick on your current configuration.