Transforming a sound in another frequency

Hello, I would like to create a plug-in that allows me to edit the words I selected another frequency, I do not know how to Nyquist.
Thank you for your help.
PS: Sorry for my rudimentary English

Sorry, I’m having trouble understanding your question. Could you try explaining the question some more.

i think he wants to freq shift vocals to change sound of voices

“Effects menu > Change Pitch” ?