Update availability may vary depending on your phone model, region, and network service provider or carrier. You can check your current phone software version by dialing *#0000#.
If a data connection is available your phone will automatically check for updates on a weekly basis and notify you when an update is available.
On phones running software version 11.1.1 or newer you can manually check for update by going to Settings > Phone update and tap on Check for updates
On older software versions you can manually force the phone to check for an update by switching off and back on the Check via mobile data option from the Settings > Phone update menu.