I need to update my iPhone 6 iOS

Your iPhone 6 already has the most up to date software that is available for that model.

It is not possible to update an iPhone 6 to iOS 15 or iOS 16 if that is what you are really asking about.

If you need to run newer iOS versions, frankly you will need a new phone.

Hello ~ You can update to iOS 12.5.7 but no further. Click on the links below….

Update your iPhone or iPad - Apple Support

If your iPhone or iPad won't update - Apple Support

If you need a higher version of iOS you will need a newer iPhone. Click below to shop for a new device…

iPhone - Apple Official Site

If you purchase a second hand device please take a moment to read these helpful links by clicking on below to make an informed decision…

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Also:

The All Too Common SAD Reality of Buying a Used iPad/iPhone

~Katana-San~

No.