Multiple displays definitely work, but I had to check regarding your question about screen arrangement. That works.
Gnome version 3.38.3
Ubuntu 20.10
Thinkpad X1 Carbon 6th gen rigged to a Dell thunderbolt dock
Monitor 1 from dock via hdmi
Monitor 2 from dock via displayport
Gnome version 3.38.3 Ubuntu 20.10 Thinkpad X1 Carbon 6th gen rigged to a Dell thunderbolt dock Monitor 1 from dock via hdmi Monitor 2 from dock via displayport