How do I get the iOS 14.0 update on my iPhone?

iOS 14 is no longer available.

• If you have an iPhone 5S or 6/6plus, the highest you can update to is 12.5.7

• If you have an iPhone 6S through 7, or SE 1st generation, you can update to 15.8.2

• If you have an iPhone 8 or X, you can update to 16.7.7

• If you have an iPhone SE (2nd generation or later), or XR through 15, you can update to 17.4.1

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

We do not know which iPhone model you are using, so can not tell whether iOS 14.0 is compatible or not.

About iOS 14 Updates - Apple Support says: iOS 14.8.1 is the latest iOS14 update.

You could check in Settings > General > Software Update to see what updates are available for your iPhone.