iPhone SE won’t instal iOS 17.0.3

What is happening when you're trying to install?

Make sure to connect to a wifi network and to turn off low power mode

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 On the iPhone 15 series, use an usb c 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. On the iPhone 15 series, use an usb c 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.

See this user tip I wrote about updating for further reference

Updating/upgrading your iPhone - Apple Community

Which model iPhone SE do you own? The original iPhone SE can only be updated to iOS 15.7.9. The iPhone SE released in 2022, can be updated to iOS 17.0.3.

Your signature says you have iPhone SE with iOS 14.

If Facebook won't run on your iPhone, then you don't even have iOS 13.4, which is the minimum required iOS version. This means you haven't updated your iPhone in a few years and it would be advisable to use the directions WheelieNick provided and update your phone using your computer (either Windows or Mac).

Only the 2nd and 3rd generation SE models can update to iOS 17. First generation is limited to iOS 15.7.1.