Fog of War only applies to the map, not to the landscape, so you won't have less fog in the game after exploring. That's just weather, or mistlands.

There are mods both for normal fog and for mistlands. I don't think the devs have any plans to tone it down. They seem to like it. There are mods for the fog of war on the map too.

Otherwise, use your ears when on land, your minimap when sailing, and the wisps in mistlands. In all three cases, slow down.