Why Can i not install..?

Go to Settings > General > About

What does it say for iPhone Model?

You need an iPhone 6s/6s Plus or newer in order to run iOS 14

Supported iPhone models - Apple Support

Update your iPhone, iPad, or iPod touch - Apple Support

issues?

Updating iOS: common issues and solutions - Apple Community

video..

Because you don’t have an iPhone?

Because you have no WiFi connection?

We can’t give you answer if you won’t provide any information or answer questions.