The baseline of the ZED2 is 120mm(4.7’’).
You can find all the information here about the ZED2 camera features and specifications here at:-https://www.stereolabs.com/zed-2/
The factory calibration is a very precise process, performed with robotics arms that place the camera in precise positions allowing it to calculate the calibration parameters with the highest possible precision.
Camera calibration is a process normally not required unless the camera has received a strong shock or you are using it inside a cover with thick glass in front of it, that acts as a lens (underwater applications for example).
We calibrate our cameras at our own office premises. It is better that you use our calibration settings. You can find more information here at Camera Calibration Settings.