The 2012 film Wreck-It Ralph is set in the world of arcade gaming, specifically as seen through the eyes of Ralph, a character in a game called "Fix-It Felix Jr." Ralph feels lonely and unappreciated because he's the "villain" of the game, and goes on a journey to prove his worth, or at the very least prove that there are others ways of measuring worth. In Ralph's journey he befriends Vanellope, a misfit character of the racing game "Sugar Rush", who has a similar ambition of proving herself.
In 2018 the film got a sequel, Ralph Breaks the Internet, where Ralph and Vanellope accidentally break the "Sugar Rush" game and journey into the massive, hectic world of the internet in search of the item they need to fix it. But like their previous journey, they discover that what they think they need and what they really need are two very different things.
In one segment of the film, Vanellope separates from Ralph and ends up in the Disney sector of the internet by herself. There, she encounters the Disney Princesses doing their thing. Vanellope befriends them and gets some words of wisdom that help her figure some things out.
Ariel is, naturally, in the CGI princess line-up, and is voiced by Jodi Benson. The other princesses whose voice actors are still alive also reprised their roles. The princesses are first seen in their familiar trademark costumes, but are inspired by Vanellope's look to dress down in modern-day clothes in what's been called the Comfy Princess Squad. The princesses also (SPOILER) reappear later in the film during a critical moment.
Ariel's been CGI before, but here she and the other princesses get to sport new looks on top of that. Ariel's comfy princess outfit is a riff on her purple-and-green combo, with her shirt bearing the text: "Gizmos & Whooz-its & Whats-its & Snarfblatts & Dinglehoppers". This could very well end up being one of Ariel's new trademark looks moving forward, who knows!