editorjs-2.x-dev/templates/ce-block--checklist.html.twig

<div class="ce-block__content cdx-checklist">
  {% for item in data.items %}
    <div class="cdx-checklist__item{% if item.checked %} cdx-checklist__item--checked{% endif %}">
      <span class="cdx-checklist__item-checkbox"></span>
      <div class="cdx-checklist__item-text">{{ item.text }}</div>
    </div>
  {% endfor %}
</div>