The colors of the sci-fi one looks a bit off because the blue color of the atmosphere/sky needs to bounce onto all the dark areas that aren’t being lit up by distinct light sources. So that whole foreground with the rocky floor and the rover vehicle need to have the blue of the sky bounced onto them, since they are only receiving light from the bounced ambient sky light. Other areas lit by light sources that are stronger than the weak ambient bounced sky light (such as those man-made lights) will be not have the blue color cast because those light sources will overpower the ambient light’s color cast.
The one with the eagle also has some problems. The light doesn’t look consistent between the trees, the leaves, the branches, and the eagle. You need to unify their light source direction and where the highlights and shadows should be.
These are some of the most important basics in understanding how lighting works, and you need to learn them if you want to produce work that is credible looking. In the workshop I teach (linked below in my signature), I give students assignments that specifically train their ability to create credible looking lighting even when they’re just working out of their head. We delve deeply into how lighting works and what are the common mistakes that artists make (such as the ones you made with these two images), and how to prevent future mistakes.