Since it looks like it was produced inside studio it’s not really a GFX design since you added a effect in some sort of editing software, you should add more characters in the ‘post apocalyptic’ you could even throw buildings in the background with some props around the area. Whether it be worn down buildings or something in the scene.
I’m sure this was screenshot and produced in studio it kind of has those parts and uneven lighting featured in the design, but if this was done or produced through a editing software, it seems a little blurry is there a reason why you made it have a blurry effect?
I would advise using Blender for rendering or learning graphic designs even choose a editing software to help with your skills in creating different types of scenes.
i took a screenshot in roblox studio and edited it in pixlr
i also added the blurry effect since i didnt know what else to add. i also dont really wanna use blender since i think its gonna be way too complicated even with tutorials.