Can I change the way the shifters move the rear derailleur (e.g. move the derailleur outboard with a left shifter click)?

Yes, the SRAM AXS Mobile App allows you to customize your shift paddle functions so that you can choose to shift down with the right or left shifter, and vice versa. You can find details on how to adjust your shifter configuration within the AXS Mobile App here: https://support.sram.com/hc/en-us/sections/1260801695990-Configure-controls-and-shift-modes