What are these techniques or common singing styles called?

Question

I am looking to know if there is a name for two "techniques" or "singing styles" that I have found commonly in many songs. The first, is a sudden change in the the voice of the singer for a particular line. Here are a few examples.

1. Cruel summer, when Taylor goes, "He looks up grinning like a devil." Here's the link with the at the right time.
2. Miss Americana and the Heartbreak prince, when she goes, "Go!", "fight!" and "win!" for the second time. Here's the link.

The second is a random onomatopoeia which the singer goes on as a tangent to the song. Here are some examples.

1. You'll be back, from Hamilton.
2. Candyman by Christina Aguilera

Answer 1

The first of the examples has nothing to do with the singer doing something different with her voice. The line "He looks up grinning like a devil" sounds different firstly because it's almost unaccompanied, and principally because there is heavy reverb on it, which makes it sound like she's singing from the back of a large room.

The technique used on the last two examples (singing without text) is most generally known as "vocalise". Closely related is "scat singing", an improvised vocalise.