The Power of Movie Musical Protagonists

In the world of movie musicals and musical episodes of TV shows, characters process their emotions and make decisions through song-and-dance numbers. The protagonists of these stories often seem to have an uncanny ability to influence people around them and make them break into song and dance.

In Encanto, Mirabelle’s gift seems to be making her family sing about their feelings, especially when they don’t want to talk about them: she makes Luisa admit she’s nervous about the Pressure, she gets the whole family to sing about Bruno, etc.
In the High School Musical series, Troy Bolton turns a basketball practice into a song-and-dance number because he can’t stop thinking about musical theatre. Then he convinces all of his friends to work at a country club even though it’s hard.

In The Greatest Showman, P.T. Barnum uses the power of song-and-dance to turn his group of social outcasts into the greatest show on Earth and to convince Zac Efron’s character to join his team.

If the songs are diegetic (the characters are aware they are singing and dancing), they are conscious choices by the characters, so they can be considered part of the characters’ development. If the songs are non-diegetic (only the audience is aware of what’s happening), they are mainly plot devices.

Other examples include Zooey’s Extraordinary Playlist, The Flash/Supergirl crossover "Duet," and The Magicians’ annual musical episodes.

Analyze the narrative impact of these characters and their musical influence. Does this phenomenon work better as character development, a plot device, or a combination of both?