I can't update my iPhone even though I have storage

The iCloud space doesn't count towards an update even if you bought more iCloud space that doesn't work, you need to check the storage space left on your iPhone in Settings>General>iPhone storage, if you do not have enough space you can remove some files or apps you don't need

To make sure your internet connection is working you can reset the network settings in Settings>General>Transfer or reset iPhone>Reset>Reset network settings, after the reset you will need to login into to wi-fi with your password again

You have a cellular data issue. See this article.

If you see No Service, Searching, or SOS on your iPhone or iPad - Apple Support

Fatt9 wrote:

My phone not poppin up cellular data for me to use my phone I have to use wifi to communicate and text can’t call out or receive calls, I’ve paid for extra iCloud storage and hooked my phone up to wifi so I don’t know why I can’t receive my update for my phone and use data on my phone

iCloud storage and device storage are not the same thing.

• iCloud storage is storage on Apple's servers, used for backups, and for synchronizing data between devices.
• Device storage is the flash storage inside your iPhone itself. Device storage is what the iPhone uses to store iOS, apps, data that isn't being synchronized through the cloud, and, in many cases, local copies of data that is being synchronized through the cloud.

You need a certain amount of free device storage to download and install iOS updates. You cannot expand device storage on an iPhone. An iPhone will always have the same amount of device storage that it had when it came from the factory. So if your iPhone device storage is too full to download an upgrade, you may need to delete things to make room.

Many iPhone 7s had a hardware issue that prevented cellular data from working. If the advice provided by sberman does not help, you should plan to replace the phone.

~Lyssa

Did you check if you have enough storage space left on your iPhone to download and install the update?