There was an article sometime back on Droid life that they will start sim locking but said it's still not effective yet. May be they started doing that now?
https://www.droid-life.com/2018/09/...-phones-for-60-days-or-life-of-payment-plans/
"The new unlock policy hasn’t yet replaced their publicly posted policy (here), but Verizon was showing the new policy yesterday on device pages. They have since removed links to it. However, we were able to access it again today on some of their Spanish device pages, thanks to our friend, Google cache.
The new postpaid policy will be put in place to “prevent identity theft and other fraudulent activities,” according to Verizon. They plan to SIM lock devices for 60 days after purchase if purchased at full retail or from a retail partner, so that they can’t be used on another network. Once 60 days is up, the lock will be “automatically” removed."