No, except for their prepaid phones. However, as mentioned above they recently required a valid Verizon sim card to activate their new phone, after which it can be unlocked. They say it's to prevent thievery, I think it's more to do with forcing people to use their network. Also, in the past a few of their prepaid phones were very cheap to unlock, like the Moto E4, this might not be true today.
But this is why I like buying Verizon phones, you have the flexibility of using Verizon network or GSM. The only caveat is for some Verizon phones the modem won't have all the LTE bands comparing to the T-Mobile or AT&T counterpart. It will still work, you may not get the maximum speed on those GSM network.