Be careful with this. These conversation engines can create something that sounds reasonable, but are actually close to nonsense. I cannot always tell the difference between a ChatGPT paragraph and one written by a random Internet user, but I can tell the difference between a ChatGPT paragraph and one written by someone who is knowledgeable in a field I am very familiar with.

It might be a good way to create a framework, but since cover letters are ultimately read by people, even a minor mistake might be enough for a potential interviewer to decide to not bring you in.

At the very least, make sure you have the entire cover letter memorized. It is really embarrassing when a candidate seems to not be aware of what their cover letter and CV say.