As the title of the video mentions, the song name is Hikari -KINGDOM Tres Orchestra Intrumental Version-, by Hikaru Utada. You can listen to it https://www.youtube.com/watch?v=tJH-7u4kAyw or https://open.spotify.com/track/3usytfZYS960Mp5DCOtZkF?si=dbf6bff4a09b452c .