First, please note that you changed the settings in your Nvidia Control Panel for all of your programs when you changed Global Settings. Instead, you should use the tab for Program Settings, then select Microsoft Flight Simulator as the program to be affected by your changes. What works for one program may not work for all -- which is what you're doing when altering Global Setting.
Personally, I keep my Nvidia Control Panel -- and the Microsoft Flight Simulator tab settings -- to default, except for enabling VSYNC. Currently VSYNC does not work under DX12 when you enable VSYNC from the in-sim graphics options. You must enable VSYNC externally through the Nvidia Control Panel. I too use TAA along with Frame Doubling.