Change the scale of outside world


I’m creating a flight simulator in Mixed Reality with Ureal Engine and Cesium and I’m facing an issue, the outside world is smaller then what it should be (ratio 1.2).
I’m not sure which parameter I could play with to just change the outside world zoom, without touching the first person model (I have a model that is representing the fuselage of the aircraft that is matching in size the real-cockpit I have in the mixed reality).

Any idea?