It uses GauGAN neural network to combine final image based on user input. There is a set of tools (materials) to use. And styles for environment setting.
Then it's as easy as painting few strokes.
You can do boring landscapes like this one.
Or play with the AI and go crazy!
I use NVIDIA Ansel AI Enhancer (free) to bring more clarity as original output is only 512x512. There are many online services but all of them are paid and the results are not as good as the Ansel AI Enhancer run on bare metal.
Bottom line is that for a first draw or searching for inspiration it is a game changer!
UPDATE: Another set