it should be possible on Sony and OnePlus phones and maybe other brands, though it can require obtaining code from internet on other device, but the device being unlocked itself doesn't need to have internet connection
I think LG had a system for getting unlock codes as well, but they closed it a long time ago.
Any other manufacturer may alter the deal any time. In case you have such a phone, dear reader, consider getting your code if you still can even if you won't use them yet.
Any other manufacturer may alter the deal any time. In case you have such a phone, dear reader, consider getting your code if you still can even if you won't use them yet.