Its the point, she got dolled up to go visit a migrant camp for a photoshoot. She was there to highlight the struggles these people are going through. To show the children being matched into the gas chambers.
Does she not own sneaker, jeans, a normal shirt? No, she dresses in an all white outfit with a movado watch. If your family member was locked up in jail, would you put on a suit and movado watch to go visit them?
This was simply a try hard situation. It looked comical that as these children lay there with Trump beating them and starving them to death, AOC puts on bright red lipstick, an all white outfit...and cant forget her materialistic watch, which in our society now is pointless other than being a fashion statement.