Step 1: Open the Settings app and tap General.
Step 2: In General settings, tap Software Update.
Step 3: If an update is available, you will see a screen prompting you to Download and Install.
Step 4: Tap Download and Install on the prompt screen.
Step 5: Enter your passcode if prompted, agree to Apple’s terms, and let the update install.
Step 6: Your iPhone will restart automatically once the update finishes installing. You will then be using the latest iOS version.