Here’s an example of how well the sky replacement can work using the AI feature in Luminar 4. It would be easy to put the wrong sky in an image such as this one. But the right choice leads to a more interesting art image. Take a look at how well the software made the selection around the juniper needles and branches. There is no sky from the original image peeking through.
If you would like to see a more in-depth review of the AI Sky Replacement Filter, you can see my post here with even more intricate selections using more sky examples.