I think you have run into a reason why the proper docking stations havie a female socket for the Thunderbolt 3 (or USB-C) cable coming from the laptop. An adapter with a pigtail lead is essentially stuck with that cable length. A docking station allows you to buy the Thunderbolt 3 cable length and type (active or passive) necessary to get the required bandwidth for your application).

Similar story for USB-C where you need longer cables.
Notwithstanding the whole power delivery aspect.

I don’t know if there is even such a thing as an ‘extension cable’ for either Thunderbolt 3 or USB-C pigtail adapters that fits within the specifications for those standards.

My own approach was to accept that the docking station and the dual DisplayPort adapters were all going to be present on the desk, tethered on fairly short cables and sort of tucked behind the laptop.

The linked article was quite well done.