@flowrider Wouldn't you need a male to female cable for Apple GPUs?
From usb c female to mini Displayport male you would use a usb c male to mDP female.
Apple Cinema 27 cable has got a fixed male connector I believe.
So something like this (with Apple GPUs):
USB C to Mini DisplayPort
Note: Apple TB2 to TB3 bidirectional adapter does not work according to apple:
"Note: This adapter does not support DisplayPort displays like the Apple LED Cinema Display or third-party DisplayPort and Mini DisplayPort displays. For more information, visit the Apple Support page for the Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter."
ps. I don't have a 2019, but I've got a 27" TB display and I'm eyeing for a 27 "cinema display at the moment.