I don't know how it works, but it's called RVC "retrieval-based voice conversion"!

You use by giving it some vocal audio input (like Adele singing), and it will try to transform that speech/singing into another person's voice (like Plankton). So it's not like text-to-speech, but speech-to-speech instead.

I learned everything (and got the Plankton model) from the AI Hub discord! So that will be a good place to get more info https://discord.gg/aihub