How do i get IOS 14.0?

If you're using an iPhone 6s or newer, install 15.6 from a computer or through the Software Update function in Settings. Older models aren't capable of it.

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If you don't have it, there's no means to get it. Anything older than an iPhone 6s/6s Plus will be maxed out at iOS 12 at the highest, and anything newer is currently OK for iOS 15.