This is official artwork from Hyrule Warriors: Age of Calamity. Princess Zelda is 16 years old for most of the game (turns 17 by the end of the game).

She's wearing a corset.

A corset is made to squeeze your waist to make it look thinner. To enhance the hourglass shape of women. With other words, it's a sexualized outfit.

So the question is: why does Nintendo sexualize a 16 year old princess?