A Wi-Fi only tablet has no way of using cellular service.
Why do you want to add it to your Verizon account exactly? What are you hoping to accomplish by doing that?
If you want to be able to access Verizon's cellular network for internet access while away from home or office even when no Wi-Fi is available like your phone can then yes you need a Wi-Fi + Cellular iPad model.
If you just need it to access the Internet at home or office on your own Wi-fi networks or with free Wi-Fi networks in places like coffee shops, restaurants or hotels etc.., then you don't need cellular, and you don't need to add it to your Verizon account at all.