I cannot download my Uber drivers app becuz my iPhone 6 iOS is 12.5.5,I need to update it to a iOS 14.0 or higherHow do I update my ios12.5.5iphone6to iOS 15.0

i tried to download my Uber drivers app to able to work , my iPhone 6 could not download this app because it has an iOS 12.5.5and to get this app you must have a iOS 14 or higher how do I up date my phone to 14 or high do I can work making delivery with Uber eats this is a crucial must have app or I stop eating and become homeless ,I’ve never own or used an iPhone very complicated and frustrating to