Hi Simme Westberg,
Thank you for reaching Microsoft Community. We appreciate for sharing your concern to us.
I am aware of your desire to connect your Surface Laptop to an external 4K 60Hz display using the thunderbolt WD19TBS dock. According to the Dell support website, the Thunderbolt WD19TBS dock requires a system with a DisplayPort (Supported) or Thunderbolt port (Recommended) rather than a USB Type-C connector that is compatible with the docking station.
Take note that since the thunderbolt WD19TBS dock is a third-party accessory, we can only provide limited details about its specifications. You may Contact Dell support for more information to see if the aforementioned accessory is functional with connecting a Surface Laptop 4 to an external display at 4K 60Hz.
Due to compatibility issues, we are unable to offer recommendations using a third-party dock with our Surface laptop. Instead, we advise making use of our Surface Dock, which is made to function optimally with our Surface devices connecting to an external monitor. The Surface Dock 2 can support Dual 4K at 60Hz.
Kind regards,
Lavenia