Square Up is a Rare Fortnite Emote. This cosmetic has been leaked, and the emote will hopefully be available to purchase in the near future! Square Up was first added to the game in Fortnite Chapter 2 Season 7.
How-to Get the Square Up Emote
Square Up was leaked or datamined, which means we don't know for sure how it will be released. Most cosmetics that are leaked will be released within 30 - 60 days of their discovery.