How do I download iOS 14

Update your iPhone, iPad, or iPod touch wirelessly

1. Back up your device using iCloud or your computer.
2. Plug your device into power and connect to the internet with Wi-Fi.
3. Go to Settings > General, then tap Software Update.
4. If you see two software update options available, choose the one that you want to install.
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7. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.

You might see that your device is up to date and that there's an upgrade available. For example, even if your device is up to date with the latest version of iOS 14, there might be an option to upgrade to iOS 15. You might want to upgrade iOS when you pair an accessory with iPhone.

If you see an alert when updating wirelessly

Learn what to do if you see an alert message while trying to update your device wirelessly.

Some software updates aren't available wirelessly. VPN or proxy connections might prevent your device from contacting the update servers.

If you need more space when updating wirelessly

If a message asks to temporarily remove apps because the software needs more space for the update, tap Continue to allow apps to be removed. After installation is complete, those apps are automatically reinstalled. If you tap Cancel instead, you can delete content manually from your device to add more space.

Customize automatic updates

Your device can update automatically overnight while it's charging.

1. Go to Settings > General > Software Update.
2. Tap Automatic Updates, then turn on Download iOS Updates.
3. Turn on Install iOS Updates. Your device will automatically update to the latest version of iOS or iPadOS. Some updates might need to be installed manually.
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Obtained from: Update your iPhone, iPad, or iPod touch - Apple Support

Hope this will help

This question needs more context. What device are you using? iOS 14 was supported the iPhone 6S and later. However, with the release of iOS 15 it is no longer possible to downgrade your device's operating system.