i can’t update my iphone 11

Why not? What happens when you try? How long has it been since you last updated your phone? If a long time ago, you may need to update using your computer with iTunes (Windows) or Finder (Mac Catalina or higher). And if you you've been using Beta, you need to remove the beta profile from your phone.

See this for some reasons why phones may not update: Updating iOS: common issues and solutions - Apple Community