I want to update my iphone6
i Want to know how to update my iPhone 6
iPhone 6, iOS 12
The iPhone 6 and iPhone 6 Plus are forever limited to iOS 12, and not supported on later versions.
iPhone 6s and iPhone 7 can get to iOS 15, and iPhone 8 is the minimum for iOS 16.
Your options here are a newer (used, refurb) or new iPhone.
Any recent of which will be substantially more capable than an iPhone 6 and iPhone 6 Plus.