Epic Games has recently stated they do not plan on implementing an FOV slider into Fortnite. Their reasoning behind this mainly revolves around the fact that players who sit further away from their screens would get motion sickness on higher FOV. This is exactly the point of making it an optional slider, so those players could stay on native FOV. However, some players, like myself, get motion sickness and claustrophobia on native, and there is nothing we can do about it.