I have just updated my iCloud storage and yet me latest IOS still won’t install, what’s up?

iCloud storage has nothing to do with built-in storage on your iPhone. Buying more iCloud storage does NOT increase the iPhone’s internal storage. Sorry.

If your iPhone is telling you you don't have enough storage to install the latest iOS then your only option is to offload unused apps, delete any other data that you don't use anymore. etc. until you have enough space.