Can I install latest version of Safari on my iPhone 8? The article that I have neglects to say this.

Safari on an iPhone is updated with the iOS version. If your iPhone is running iOS 14.3 it has the most up to date version of Safari.

The version of Safari on an iOS device is determined by the version of IOS installed. If you have the latest version (iOS 14.3) you have the latest version of Safari for iOS.

Since you have iOS 14 installed, you also already have the latest version of Safari installed.

There also isn't a way to piecemeal what system software gets installed on an iOS device.