You might even be able to go into World Manager and make a 'Fashion Squad' on the sim in question or change other things with codes, but there could be an easier way to control your entire world and not just a sim or a family of them. You just want to change that right away or just send her off the lot as soon as possible.
Of course, even if you understand that the world of sims is a fanciful, over-the-top world, seeing a sim walking around in a weird outfit, half a classic purple wedding dress paired with half a lime green clown costume, and a cowboy hat on top is not the most pleasing thing to the eye and it breaks the immersion in the game too much when that freak is on screen. It is interesting and fun to see the behavior of these figurines that live in worlds that resemble the North American suburb, with small houses with white fences and gardens. The Sims 4 is a game about living a different life, in a crazy world, full of aliens, vampires and people with very weird habits where you can be friends with death.
