External Thunderbolt Display HiDPI resolution (Retina)

I have a MacBookPro running Catalina with an external Apple Thunderbolt Display. I have connected to it using a Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter.

When the lid of the MacBookPro is open, I can mirror the screen and get an HiDPI resolution of 1920×1200 in the Thunderbolt Display.

When I close the lid of the MacBookPro (which is my preferred arrangement), the maximum HiDPI resolution I can select is 1280×800. The maximum resolution of the Thunderbolt Display I can select is 2560×1600, which is too fuzzy and the text is too small. The maximum resolution of the display is 2560×1440 according to the "About this Mac" report.

My question is, how can I get to the 1920×1200 HiDPI resolution when the MacBookPro lid is closed?

I have tried SwitchResX, but it can’t solve the problem.