coooooooooooontraaaaaaaaaaaaaaaaaaast
laaaaaaaaaaaaaaaaaaaaaayeeeeeeeeeeers
your backgrounds are really nice, but currently they look like 3D CAD drawings without the final finish. so your things arent overly flat in their contour, but the lack of shadows and lightness of those that exist, the stark midday lighting, takes away from the mood.
the great thing about the concept art youre drawing inspiration from, in part, is its concentrated and directional lighting. the light areas are light, the dark areas are very dark. also, theres an overall colour tint that comes with light - photographers prefer to shoot in the early morning and late evening, the "golden hour" because the colour temperature of the light is lower, more golden, and gives things greater richness.
In that last image you shared, the palette is overwhelmingly green with a little blue, not exactly because the light is, but because of reflections from the grass and the sky, and it gives a greater sense of place (and time and temperature) as well as making an altogether more appealing image
so, consider the direction of and nature of your light - the longer the shadows and more concentrated the point of light (hence greater contrast) the more dramatic it is, and light guides the eye. you want the focal point of your image to be clear when you squint. and limit your palettes down - maybe in reality things are all sorts of colours, but if you look at films and comics with good / stylised (same thing to me, but that is just me) use of colour, that isnt the case. colour is streamlined for mood, meaning, and making comprehensive images.
another great thing these concept paintings do is layer up their landscapes to create greater depth, in a more mesmerising way.
(source, a really great comics workshop)
this ties in with their use of shading - the foreground is darker, higher contrast, key features standing out against the lighter backgrounds, and the further back you go the lower the contrast and lighter the layer. thats how you get that stunning depth
have you studied these paintings you wanna draw from? made copies? copying an artist you love (AKA transcription or master studies) is the best way to get an understanding of what they do so well
also, research into composition, contrast, and depth - theres lots of great resources out there to help you if you look