To darken the ambient occlusion in baked lighting, you should:

Increasing the Ambient Occlusion amount enhances the darkness in the ambient occlusion effects within the baked lighting of your scene. Ambient Occlusion (AO) simulates how much ambient light reaches various parts of the scene, particularly in crevices and areas facing away from the light sources. By increasing the AO amount, you effectively amplify the effect of shadowing in those areas, leading to a darker and more pronounced occlusion effect.

This adjustment gives depth and realism to the lighting by helping to define shapes and contours, particularly in areas where light naturally struggles to penetrate. As a result, the overall visual quality improves, making the objects in the scene appear more three-dimensional and grounded.

In contrast, the other options do not directly contribute to darkening ambient occlusion. Adjusting light intensity influences the overall brightness of the scene but does not specifically affect the AO effect itself. Changing shadow quality pertains to the sharpness or blurriness of shadows rather than the ambient occlusion level. Reducing the Ambient Occlusion amount would have the opposite effect, lightening the areas that are currently darkened by the AO effect.