In this tutorial from the Epic Online Learning team, you’ll create your own unique map for a capture the flag game in Fortnite which you can then take and put your own spin on. Utilize the assets included with UEFN and playtest your own customized level!
https://dev.epicgames.com/community/learning/tutorials/1x1r/fortnite-creating-a-capture-the-flag-game-mode-in-uefn