Defining email template with text or html type in plugin



I want to register an email template in my plugin. And I have a text and a html variant.

But i dont think i register these templates in my plugin.

I created the follwing files in my plugin:

And in my plugin registration i have this:

    'template' => [
        'emails/mail' => __DIR__.DS.'/templates/emails/mail.php',

But my email template is never found. Which is correct of course because the mail.php doesbn’t exist.
But now i cant send mails using this code:

                'template' => 'mail',
                'data' => [
                    'body' => $body,

Can i create html/text email templates in my plugin?
Or is it missing for now in the plugin registration.