One of the best photo processors is Darktable, and one of its advanced features is masks. A mask in photograph processing gets used to limit adjustments you make to an image to just one area of the image. The linked article shows how this is used.
See Open source photo processing with Darktable
It's hard to say how good photographs happen. You have to be in the right place at just the right moment. You have to have a camera at the ready and an eye for composition. And that's just the part that happens in the camera. There's a whole other stage to great photography that many people don't think about. It used to happen with lights and chemicals in a darkroom, but with today's digital tools, post-production happens in darkroom software.