The default value for Sky Strength, configured in the Bake tab, is geared towards interior scenes, but when used for exteriors it may lead to an overly bright image. Reduce the strength to 0.5-1.5.
Reduce the Lightmap resolution to 10-20
Similarly, the default value for Lightmap resolution, also configured in the Bake tab, is usually too high for exterior scenes because it produces multiple lightmaps, which cause long baking times.
Exteriors, which are usually viewed from a greater distance than interiors, do not need such detailed light information, so the lightmap resolution can be reduced to 10-20.
