How do we update to ios 16 if we have iphone 6 ios 12.5.7

Sorry, but the iPhone 6 and 6Plus can't be upgraded beyond iOS 12.5.7, the built in hardware does not support that.

You will have to buy a newer iPhone model.

iOS 13 and iPadOS are compatible with these devices - Apple Support

iOS 14 and iPadOS are compatible with these devices - Apple Support

iOS 15 and iPadOS 15 are compatible with these devices - Apple Support

iOS 16 and iPadOS 16 are compatible with these devices - Apple Support

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~

16

Hello~ Read the previous posts *Ingo2711* and myself. They should fully answer your question.

~Katana-San~

No