https://www.artstation.com/marketplace/p/9nAP6/environment-concept-art-vol-1-overpainting-photobashing-and-refining-keyarts

This tutorial will give you an insight about the process of finishing an environmental concept keyart. From the raw image straight out of the renderer to the final concept art, heavily based on cinematic look and feel. Using techniques of painting in details, using photobash to enhance and change the image, creating decals and illustrative elements, using and painting VFX to final colour correction and using steps to finalise a finished environmental concept keyart. Everything narrated in a live demo and explained to follow the process from start to finish.