can i mirror my iphone screen without wifi?

Airplay is a protocol that works over wifi and typically requires both devices be on the same network. In situations where that is not possible you can use peer to peer to connect devices on different networks, where it will use bluetooth to discover and then wifi to create an ad-hoc connection between the devices.

Smart TV's can support airplay so there will be options for that, but it doesn't mean that it can be used without a network connection.

No