Here are some guidelines for setting up realistic lighting in color-managed scenes.
For realistic results, it is recommended that the Decay Rate of scene lights be set to Quadratic to mimic the behavior of light in the real world. Although this setting can make it difficult to find a balance between highlights and shadows when you are not using color management, it is not a problem when rendering in a scene-linear color space. However, you may need to adjust the lights' Intensity depending on the scale to which the scene was modeled as well as the distance to the lights.
In addition, it is recommended not to use any ambient lighting in the scene. Ambient lights are a quick but unnatural substitute for indirect lighting.