There are two kinds of thinking. Normal and deep.
Normal is taking the directions you were given to go somewhere. Deep is when you push deep into a subject and truly understand it, you go well past where most people would think would be enough. You understand the traffic patterns and the entire city map, you know why you were given the directions you were given.
If you want to be a writer you have to be a deep thinker. The only way to make a setting feel real is to make it deep and wide, you won’t show but a small part of it but you can’t just think about that part.
A society is not a jumble of unconnected things all taking place at once, its a complex system where everything touches everything else. Morals effect clothing, but so does utility and the economy. You can’t get everything but you should aim to go deeper then the average reader, so deep that your reader will never see the bottom.
The same goes for your characters, think about what motivates them, why they have their mannerisms, what their biggest disappoint in life was.
Again you don’t have to show everything, showing the tip is enough.