I don't think there is a single specific term for what you are asking for.
Music structure is all about dynamics, and how they interact. If somebody asked me to describe your two examples to help find something similar, I would just say they "build to a climax".
It is common parlance for people to say "build to a crescendo", which is ...
Perhaps you mean Leitmotif.
The term originated in musical theatre, and has been used in movie scores. It's a short, repeated, piece of music that signifies a particular character, location, or object. It is played when that character does something significant.
Discussion of Leitmotif in movies.