I bought a 16mm Lens for HQ camera Raspberry pi and when I tested it gave me a zoomed picture, I don’t know if I can adjust the zoom? and How can I change the FOV of this lens because I have 4 options :
Field Angle 1"
Field Angle 2/3"
Field Angle 1/1.8"
Field Angle 1/2"
44.6° × 33.6°
30.0° × 23.2°
24.7° × 18.6°
21.8° × 16.4
Thanks 
The tables above give the approximate field of view that the 16mm lens will provide when used with different sensor sizes.
The IMX477 sensor used in the RPi HQ camera is a 1/2.3" sensor and the fixed focal length lens will give a field of view of approx 22.2 x 16.7 degrees when used with this sensor.
There is no way to change the maximum FOV of a fixed focal length lens when used with a fixed sensor size, so you are stuck with this single FOV.
To get a wider FOV you need a shorter focal length lens. e.g a 6mm lens will give a more ‘normal’ FOV of approx 55 x 41 degrees. (Or of course use a ‘zoom’ variable focal length lens if you need adjustable FOV)!
HTH