I was inspired by the switchable sky that Joakim Stigsson (https://www.artstation.com/joakimstigsson) showed in his Golden Gas Station breakdown here, https://www.artstation.com/artwork/1Pr48
Took me a while to figure it out but managed to do a quick set up in Blueprint without any post-process. I can control fog, contrast and colors of the sunlight. I'm adding more fog controls, post-process controls, and two more sky types (Starry Night and Day) to create a handy lighting setup for testing out environments and assets. It uses custom sky material setup based on the one that comes in starter content. I used Nuke to clamp some brightness values of HDRIs to avoid any overexposure.
Sky Blueprint Test