This idea is to have built-in email functionality, sending a confirmation message to the user when they hit Submit in the form. This is standard functionality in many systems that lets the user know that the submission worked and also gives the user a record of their info for future reference.
Built-in email functionality would be more robust than integrating to an outside system like Power Automate via webhooks.
The form would have a mandatory user email address field and a captcha.
Related: Built-in Survey123 email notification (to staff when survey submitted)