To rotate the screen on an iPhone from portrait to landscape mode, follow these steps:

• Unlock the iPhone using Face ID, Touch ID, or passcode.
• Open the app you want to use that supports rotation, such as Safari, YouTube, or Photos.
• Hold your iPhone horizontally.
• If auto-rotate is enabled, the screen will automatically switch to landscape mode.

If the screen does not rotate:

• Swipe down from the top-right corner (on iPhone X and later) or swipe up from the bottom (on older models) to open Control Center.
• Look for the Portrait Orientation Lock icon (a lock with a circular arrow).
• If the icon is highlighted, tap it to disable the orientation lock.
• Once disabled, the screen should rotate freely when you turn the device sideways.

If issues persist, try restarting the iPhone or making sure that Display Zoom is set to Standard in Settings > Display & Brightness > View. This method works on all modern iPhones, including the latest models like iPhone 16. Some apps or the Home Screen may not support rotation. This covers enabling and troubleshooting iPhone screen rotation.