Why, in my head obviously /s. Joke aside, pressing DEL key should open vorpX menu while playing in VR and you can tinker with all the settings in there, including FOV, though from memory Ralf (vorpX dev) would tell you not to change those settings as they should already be the best by default and in the games where .ini files are changed you would get the according notification pop up in the corner of the game telling you about it; in any case it is better to change it through the game itself and not from vorpX.