Q: What does a chorus effect literally do to my audio?
A: It's basically digital cloning.
The tool takes your original audio file. It magically creates a few identical copies behind the scenes. Then, it ever-so-slightly detunes those copies and delays them by a microscopic few milliseconds. When everything plays back together, it violently tricks your ears into thinking a massive group of people is singing at once.
Q: Does chorus only work on human vocals?
A: Not even close. It is absolutely legendary on electric guitars and synthesizers.
If you play a clean electric guitar track and apply a thick chorus effect, you instantly get that dreamy, watery, classic 1980s pop sound. Throw it on a basic synth waveform, and it instantly transforms into a massive, thick, stadium-filling analog pad. It essentially adds instant "thickness" to any thin sound.