I just have a door that automatically opens/closes with sunrise/sunset. My chickens have never been caught outside.

A couple of months ago, I had to replace the roof on their coop and locked the door so they couldn’t get in and get hurt (they are intensely curious whenever anyone is inside their coop). Construction ran into the evening, and the poor birds were visibly (and audibly) upset about not being able to go inside once it got dark.

They’re smarter than people give them credit.

Unless you have too many to do this, you just need to show them in the first couple of nights, and after that they pretty much help themselves.