The Twig include tag lets you pull one template into another, and it allows you to pass & transform data in the process using with in the tag like {% raw %}{% include 'file.twig' with { item: true } %}{% endraw %}. This can be used in the embed tag or the extends tag as well.

This gives us the opportunity to map the data; for example:

In templates/block--system-branding-block.twig:

{% include "@molecules/blocks/branding.twig" with {
    url: path('<front>'),
    text: site_name,
  }
%}

In pattern-lab/source/_patterns/02-molecules/blocks/branding.twig:

<a href="{{ url }}">
  {{ text }}
</a>