A leitmotif is when the same soundtrack plays multiple times in a film to introduce the same idea or movie.

In THOR RAGNAROK the same soundtrack was played at the beginning of the movie when Thor was at the peak of his abilities and his power was unmatchable and through the film we get to see Thor’s powers fall; towards the end however, the same soundtrack starts playing when his powers rise and grow again indicating a sense of power and confidence making him seem unstoppable.