You can include any custom fields in the Enroll Form in the Enrollment confirmation email!
In the "Other Settings" in any custom field setting are two additional options:
Include in the confirmation email - This is the enrollment confirmation (welcome) email sent to the Primary Account Holder
Include in the new enrollment email - This is the email sent to one or more Admin Users after a person has enrolled
To learn more about customizing your Enroll Form, check out this support article.