"Copy" is a silly way of putting it, but yes, they're trying to compete with ROBLOX in that Epic is trying to turn it into a child-oriented general entertainment platform as opposed to just a child-oriented Battle Royale. They started doing this a while back when they were pushing the UE4 user gamemodes, and recently with Festival/LEGO/Rocket Racing they're trying to place more emphasis on it as a general "game development" platform in a similar vein to ROBLOX. Because of the way Fortnite generally just sort of plays and the closed nature of the tools they give you it's not really the same thing; you still feel like you're playing something that branches off of Fortnite as opposed to a game on a game development platform.