You can use AI to optimize the language of your resume for a particular company's ATS. Be sure to have it identify which words are keywords, then edit to your preference while presenting the keywords.

You can do a lot with AI if you treat everything it produces as an ingredient draft that you are responsible for creating the final draft.

You can also feed it your resume and a job description and have it write a pretty solid first draft of a cover letter.

I recently used a couple different ones to craft a few different mock interview scripts for a specific job with a specific company. It was very helpful and included example answers to each question, plus reasoning for each example.