You say "my song". That is an important context.
The idiomatic choice here is not reach out to but simply reach.
Do you think the song will reach everyone?
A person listening to the music can say
The song really reaches out to me.
The song really reaches me.
The phrase reach out to expresses something that you as the composer would do (you would reach out to the audience through your music) or something the audience feels about the music (they feel the music reaches out to them).
The composer will know if he or she is trying to reach out to people, and so a question posed by the composer, using reach out to, must be about how the audience will feel. The composer could ask:
Do you think people will feel the song is reaching out to them?
Do you think the song will reach people?