Charisma has two halves.
It’s a relationship between the person who possesses it and the people who respond to it. It’s only when the spark meets the kindling that a flame can ignite. A charismatic speaking to a mirror is not particularly exciting. Put one in front of a crowd, however, and you’re in for a show.
Emotion is the accelerant.
In fact, beyond shutting down our ability to reason, some scientists have found that under the right circumstances, charismatics—especially if that charisma stems from our perception of them as a “leader”—can induce a state akin to hypnotism.
Source: What Makes a Person Charismatic?