You could have a visibility slider in theory, but it has to be tied to a reference point in the world. It can’ t just be a “global visibility” in a preset unless you want a visibility circle to follow your plane through infinite fog. Like I mentioned above, one simple approach would be being able to modify the METAR reports and set your own values, which I would imagine wouldn’t require much extra work. Or be able to specify coordinates, a radius, some parameters, and the sim automatically fills in the atmosphere based on the parameters and radius you set. Another option is a map that allows you to set each cell of the atmosphere, creating more advanced scenarios that could be useful for bush flights or missions.