Why Isn't My iPhone Home Screen Rotating?
As of this writing, the iPhone 6 Plus is the only iPhone with home screen rotation enabled. If you have an iPhone 6 Plus and it's still not working, you might need to adjust a setting. Launch the Settings app on your iPhone and navigate to Display & Brightness. Tap View (under Display Zoom) and then selected Standard instead of Zoomed. You should now be all set. Although if this still doesn't work, double-check to make sure that your Orientation Lock is not turned on.