A:Answer Simple answer NO, it does not have to be tied to a plan if you purchase the unlocked phone. Otherwise read the fine print.
You can purchase an "unlocked" phone for less upfront money, however, if your wireless carrier is Verizon you will NOT get the HD calling, Video Chat, Messenger+ features, contacts lists, just to name a few. They cannot they be added to an "Unlocked" phone. My experience with Verizon Tech support was not the best since I did not purchase it from them and they are under no obligation other to refer you to where you purchased the phone for any phone related issues.
If those Verizon branded features are not important then the unlocked phone may be the cheaper opinion (as of July 2019).
BestBuy does have the branded Verizon phones and other carriers that are occasionally at a reduced price.
Hope this helps...