How I update my software

Assuming it hasn’t already been updated to iOS 12.5.3, see: Update your iPhone, iPad, or iPod touch - Apple Support

The latest IOS is 14.6

You can go to Setting-General-About to check on which IOS you are and if its not IOS 14.6 then u can update it by going to Settings-General-Software update.You can only update over Wifi and make sure that ur device is atleast charged 50% or plugged into the charger.Hope this helps.

Sorry i did not see its an Iphone 6