There is no plugin that supports this directly.
What you can do is to create a custom field with long text. This text will be the custom content of your email.
Create a function in n8n that receives parameters (including contact id) calls chatgpt, creates the content and pushes the custom content into mautic via api.
Now create a campaign that passes the parameters to n8n via webhook.
The webhook will activate the n8n function, and mautic will receive the updated custom content via api from n8n. The second campaign step can be sending the email with the custom content token.