use this plugin for emails sent from my child theme or plugins

I develop a solution based on WP which is a kind of LMS (Learning Management System).

In this solution, there are multiple situations where emails need to be send to users:
when their account is created
when they are registered in a group
when they are registered to a course
when they complete a course
and so on
I am looking for a solution which provides features for:
1/ easily design the email templates used by these emails
2/ send customized emails using email templates with variables or shortcodes (user first name, last name, course title, course score, etc.)
3/ send email from child theme or plugin, and be able to select which email template is used to generate the email
Please tell me which features your plugin provides and if possible a link to the documentation on how to do it.