First, the answer to your question is no, you cannot change the cameras for another type. And with regard to the zoom, it is not usually provided on a consumer level drone, as the gimbal stabilisation would not be good enough. DJI do have a zoom option as shown in the link above, but it is for their professional level drones.
The camera of P3 and P4 are not compatible. And P4 supports a 2x digital zoom, but does not support optical zoom. You can zoom in or out by dragging on the screen or by pressing the customizable buttons.