You could download a fov changer and use that wich is very simple tp use and there is oftrn a manual on the website or somewhat of a guide. But then agin, nlt sure if this was allowed or not.
But if you wanna try if you just google FOV changer and armaholic should have one I used a while back on exile and Koth.
Then once you're finished all you need to do is open it and it should look somehwat like this
Step 1. Press select at the top and it will open all your files and such. You then go to documents and as seen on picture 2 you press arma 3 other profiles. Then you press on the rpofile you play with. Then you press on the profile that ends with ".Arma3Profile" as seen in picture 3. After that's done all you need to do is fill in your screen resulotion and then at the bottom you just write in the FOV you want then you press "Change FOV" and then you're done
I think it was @SlimShady who also knew a way to do this in the arma 3 files.