How to zoom in / out the field of view when aiming using the iron sight in arma cwa 1.99?

[MaxxPayne95 1]

I was testing SLX 1.1 and ffsx 85, and both mods has a feature that allows you to zoom in or out when aiming the weapon with the V key by default, and I would like to use that same feature in vanilla mode, because in SLX and ffsx 85 I have low FPS or lag due to the graphical improvements that those mods have. So what could I do to have that feature in vanilla mode? is there any addon or file that allows to do that?