Verizon prevented two of my unlocked phones (Nexus 6P and Moto G6 Power) from using WiFi calling, likely because I didn't buy them through them. The phones were perfectly capable of it but it was just some carrier config that prevented it. I bought an unlocked Samsung A53 and that is suddenly allowed to use WiFi calling, likely because Verizon sells the exact same model. I went years without WiFi calling despite living in two homes that had awful cell signal. Now I have a phone with the feature but have great home cell signal.