This is just linear advance pressure calibration or flow dynamics as bambu calls it. For non flexible pla it shouldnt matter default will work fine. But you could potentially get slightly better results running a calibration which saves the value specific to your filament. That is what you are seeing with the 1 2 3 options. Your question isn’t really related to the thread as it is already a supported feature. We want the A1 series to support custom filaments from other brands like sunlu on the printer’s own ams menu to save a lot of annoyance when using the slicer.