I was given 4 Verizon XS Max in December. Two of them were unlocked straight out of the box and the other two were unlocked within two hours of using the phone with the Verizon sim in them. I verified that they were unlocked by starting up the T-Mobile eSim app. Once they were unlocked, the app instructed me to setup an eSim account on T-Mobile. I backed out and used my T-Mobile sim with no problems.
The other two were unlocked out of the box and I knew this because out of the four, only these two activated with my T-Mobile sim upon booting them up the first time.
I am using two of those phones today with no problems.
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.
Basically, Verizon has started locking phones just for the short period such as what I mentioned above. Even with the Pixel phones, they were locked for 24hrs then they would be unlocked and people started complaining about that so Verizon waived the 24hr lock period for a short time.
Verizon started doing this because too many people would get phones for zero down, skip out on paying for the phone and the account and move out of the country or ship the phone to be sold.
Their policy states that they don't lock phones but it's just for the short period, for me, my iPhones were locked for barely two hours.