Here are some guidelines for setting up realistic lighting in color-managed scenes.
Achieving realistic lighting is greatly helped by selecting a view transform that uses proper color science, such as the ACES-recommended view transform. These transforms apply an S-shape curve (or tone map) that gradually rolls off highlight values to prevent harsh clipping. They also apply other corrections advised by color-science best practices, such as the correct placement of mid-gray. Primitive view/display transforms that only apply gamma correction are insufficient because they clip all values above 1 and have other problems that make it difficult to properly light a scene.
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.
When using any form of image-based lighting, make sure that the Color Space corresponds to the correct value for the image file that you are using. Raw usually works for the type of image files commonly used for IBL. However, it is best to specify the exact color space used so that colors get properly converted to the rendering space if it is different from the file's space. See Add color-managed textures and other image inputs.