Does it use iCloud to update the iPhone and iPad?

I don't really want to use it up, and what can you do with icolud!

IOS updates are over the internet and are not linked to iCloud. But there's no limit to iCloud, so even if it was using iCloud services, there's nothing to "use up"

The storage limit on iCloud only applies to stuff like backed up data and iCloud documents. And if it fills up you can delete the stuff you don't need, but 5gb is usually more then enough free storage