How to fade in or out when using Set Visibility?

My project relies on lights transitioning between off and on, to different colors, etc. For example, the general lighting setup starts out as a blue midday look, and ticking a variable will (hopefully seamlessly) change it to an orange sunset look. Changing between lighting “schemes” involves several different components (lights, sky sphere, and post process volume) being turned off and on.

Right now I have all of the components of my blue color scheme hooked up to the “Set Visibility” node to toggle them “on” or “off”. “Set visibility” is an easy way to turn them on/off all at once, but I want there to be a smooth transition, like fading their visibility in/out, when I do it. Is this possible? I thought it could be possible to do it with a timeline but I’m not sure how.

Alternatively I can manually set the intensity of the lights up or down with a timeline in order to create the smooth fade, but I don’t know how to set the sky spheres and post process volumes with a timeline…

Thank you!