Wanna update my iOS from my old iOS to at least 13.4

An iPhone 6/6 plus can't be updated beyond 12.5.7, it doesn't have the hardware needed to run anything higher.

If you need a higher iOS version, you will have to purchase a newer phone.

To update to 12.5.7 -

Go to Settings > General > Software Update.

This link will show you how to update your iPhone, iPad, or iPod touch using WiFi -

Update your iPhone or iPad - Apple Support

This link will show you how to update using your computer -

Update iOS on iPhone - Apple Support

leovela Said:

"Wanna update my iOS from my old iOS to at least 13.4: Please updating my old iOS to 13.4 how to upgrade?"

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Please Provide More on your iPhone:

What's you iPhone model? What are you looking to update to? Without that being provided, read the following...

Updating an iPhone to iOS17:

Update Using a Computer:

What to Update: Installed apps and the iOS.

How to do so...

A. Verify Compatibility:

Identify your iPhone model. The first thing that comes to mind in incompatibility being the culprit. So, confirm the model of your iPhone. If iPhone model is incompatible with iOS 17, then it is because you iPhone does not meet the hardware requirements for this iOS version(s).

B. If Compatible...

1. Back Up First:

IMPORTANT: If you have an option to update, however, then be certain you backup your iPhone first. That way, you will have something to restore your iPhone from should anything go wrong with the update

then...

2. Proceed with the Update:

Go Here:  Update your iPhone Using a Computer - User Tip

I want to update my iOS 12.5.7 to 13.4

I want to update my iOS 12.5.7 to 13.4

No, it is not possible.

You need an iPhone 7 or higher model.

ayodeji106 wrote:

I want to update my iOS 12.5.7 to 13.4

You can’t. You need a new phone.