theming – Customized email twig templates

Can anyone tell me if there is a mechanism for creating user registration acceptance / rejection emails from different template files for the default email system ?

In admin/config/people/accounts, the account activation section seems the correct area for crafting the registration acceptance email. BUT, I don’t think anyother section is right for te registration rejection email.

So, I tried to find a means of using twig templates for a various scenarios I am trying to fufil without success. Webforms seems to have this functionality but I need it for the default drupal email system.