I want to update my phone

The iPhone 5S/6/6plus cannot update further then iOS 12.5.7

The iPhone 5C/5 cannot update further then iOS 10.3.4

The iPhone 4S cannot update further then iOS 9.3.6

The iPhone 4 cannot update further then iOS 7.1.2

The iPhone 6S/6Splus cannot update further then iOS 15.7.8

The iPhone 7/7plus cannot update further then iOS 15.7.8

The iPhone SE (2016, first gen) cannot update further then iOS 15.7.8

First, check if you've an available iPhone for updating in the chart above. As you can see, the latest iOS for the iPhone 5 is iOS 10.3.4

If you have another iPhone then an iPhone 5, and it is eligible, go to settings>general>software update. If you see "this iPhone is up to date" there are no avaliable updates for you

If there is an update,please turn off low power mode and connect your iPhone to a wifi network. If updating wirelessly is not working, please update via a pc or Mac instead

Update your iPhone using a Mac with macOS Catalina or higher

On a Mac with macOS Catalina or higher, you will use the finder in order to upgrade your iPhone. Make sure to Back up your device before starting the upgrade process.

On a Mac with macOS Catalina or later, you will follow the following steps:

1. Open a finder window
2. Connect your device to your Mac via a lighting to usb A or a lightning to usb c cable
3. Select your device in the left sidebar of the finder window
4. click general, then click check for update
5. Click download and update.
6. If asked, enter your iPhone passcode

Update your iPhone via a Mac running macOS Mojave or earlier, or on a Windows PC

On macOS Mojave or earlier, or on a windows machine, we won't use the Finder to upgrade your iOS

Instead, we will use iTunes. Make sure to Back up your device before doing any update or upgrade to your phone.

1. Open iTunes
2. connect your device to the computer with an lightning to usb a or a lightning to usb c cable
3. Click device button in the iTunes toolbar
4. In the summary tab, click check for update
5. Click download and update, follow The on screen instructions
6. If asked, enter your iPhone passcode.

Updating/upgrading your iPhone - Apple Community

Your tag line says that you have an iPhone 5. That iPhone can’t run iOS 15.7.8. It can run iOS 10.3.4, but not iOS 11 or higher.

That's not technically possible on an iPhone 5, sorry.

See why in this compatibility list:

I won’t to update my phone

My phone can’t update

Did you read any of the answers? If you have an iPhone 5, your phone is not qualified for an update.

No updates for the iPhone 5.

You need a new phone.