If device was purchased unlocked(not attached to any carrier) then some carrier features won't work. Video call is one of them, VoLTE, Advanced messaging, so not all carriers will support all features on unlocked models
Unfortunately carriers bend the knee to Apple and let them do whatever. I wish that was the case with Samsung as well. Most of the android based phones are loaded with apps that you don't need. Carriers limit what android phones can do because they can get away with it. The video call feature isn't that great through carriers anyway. Google Duo is better in my opinion. Factory unlocked phones is the way to go if you can afford it.