Should there be some indication that additional form fields are available for the email templates on the Account Settings Form

Problem/Motivation

During work on #85494: Use email verification when changing user email addresses and as part of #3263897: Drupal Usability Meeting 2022-02-18, it was identified that because some email templates on the Account Settings form use progressive discovery, it is not always clear that those fields exist.

In the specific case where the checkbox to enable an email template is unchecked the email template body field is not shown. In this case the UI does not make it clear that this additional field exists and that the template can be edited.

If the user wants to change the body of an email template where the corresponding checkbox is unchecked, the user would have to know that the body field exists, and would need to check the box to show the body field, make their changes, then uncheck the box again before saving. This could cause confusion, for example if the user wants to change all of the email templates, but because some body fields may be hidden, they may not know where to go to change those templates.

This behaviour could also be a problem because it creates inequality between changing something via configuration and changing something via the UI. When the user changes the same field via configuration, it doesn't matter whether the box is checked or not, the user can still find and change the field.

Steps to reproduce

Proposed resolution

Remaining tasks

1. Discuss if this is even something that we should be concerned with.
2. If so, design a solution.

User interface changes

API changes

Data model changes

Release notes snippet