In my experience the ThunderBolt 3 cables are the ones you want to plug into your laptop and route nicely behind it so you can tuck your dock somewhere aesthetically pleasing... but they have a 10cm bend-radius and are only 40cm long.

They're also usually marked with a little ThunderBolt and also perplexingly a little "3" presumably in case there's a ThunderBolt 4 sometime in the future that's mad enough not to release with its own connector specification.