How to do the update

On the off chance you are referring to your" iPhone 6s, iOS 13 " ?

Update your iPhone or iPad - Apple Support (CA)

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

Use a computer or the Software Update function in Settings. If you encounter a specific issue, describe it in this thread.

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Qhurphithiago wrote:

How to do the apple software update

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Update macOS on Mac

Keep your Mac up to date