How do I connect my iPhone to my vizio smart tv to watch movies

It still is.

option 1. Buy an HDMI converter cable, if one exists for the iPhone, this is your WIRED solution.
option 2. Buy an AppleTV, a box that you, again hookup TV via HDMI, the iPhone will wirelessly talks to Apple TV box. The Apple box will have the capability of buying/renting movies from the iTunes store and other sources all by itself without the phone.