fontawesome-8.x-2.x-dev/templates/fontawesomeicons.html.twig

{#
/**
 * @file
 * Default implementation for Font Awesome icons.
 *
 * Available variables:
 * - icons: a list of Font Awesome icons to be rendered.
 * - layers: flag indicating if icons are printing as layers.
 *
 * @ingroup themeable
 */
#}
<div class="fontawesome-icons">
  {% if layers == '1' %}
    <span class="fa-layers fa-fw">{{ icons }}</span>
  {% else %}
    {{ icons }}
  {% endif %}
</div>