Each character will have an individual way of reacting to and observing the world.  These are the details you as the writer can use to reveal both your world and your character.

The details any character will notice depend on that character’s personality, interests, needs, relationship with other characters, and their cultural landscape, the way they look at the world.

If Cat is hungry (and she’s always hungry), she will notice food, describe food, and be interested in the presence or absence of food.  If Mai is shopping, she will notice silk, its quality and weave and its color and the quality of its dye.  Anji will always be aware of where people are standing in relation to him and his people, and whether those others present a threat.

Another character may not notice those very same things even if they are at the first character’s side, or they may register them in the most cursory sense.

Another character might be more of a listener, attuned to sounds.  Another might only really notice people and their reactions rather than noticing space and setting.  Another might not notice much of anything, being more involved in their own thoughts.  A character who lives within a culture will notice different things about what’s going on around them than a traveler new to the culture.

When you as the writer start thinking about filtering details through the characters’ point of view, it becomes easier to decide which details are necessary to the story and which you don’t need.