How to download iOS 12.0 version in iPhone 5

ios12 is too advanced for iphone 5. Cannot be done.

if it's an iPhone 5s, then you could.. otherwise, you cannot.. I think iOS 10.3.3 is the last update for an iPhone 5

iOS 10.3.4 is as far as you can go with the iPhone 5. If that is already installed, you have reached the end of the update road.

Hi, I think you can’t update your iPhone 5 to iOS 12.

On the link below you can find everything you need to know about iPhone software updates.

Apple security updates - Apple Support