How to use a slider to adjust overall brightness/darkness, including the skybox?

Hello, folks.

I’d like to know how to include the skybox while adjusting brightness.
I set the slider to adjust light intensity. The scene keeps only with the Environment lighting (which I would like to control together also) and the sky keeps illuminated.
Thanks for your help!!

If you are rendering with HDR enabled, you could add the tonemapping component to the camera and change the exposure. Without HDR this would mean a loss of color detail, but you can try that too.