Code for section which generates related products based on matching handles and tags - https://www.shopify.com/partners/blog/related-products

related-products-by-tag-handle.liquid

<hr>
<div class="product-template__container page-width" itemscope itemtype="http://schema.org/Product" id="ProductSection-{{ section.id }}" data-section-id="{{ section.id }}" data-section-type="product" data-enable-history-state="true">
  <h3> {{ section.settings.related_title }} </h3>

  {% assign image_size = 'medium' %}

    {% if product.tags.size > 0 %}

      {% include 'snippet-for-related-products' %}

    {% endif %}   
</div>
<hr>


{% schema %}
{
  "name": "Related products",
  "settings": [
    {
      "id": "related_title",
      "type": "text",
      "label": "Section title",
      "default": "Other fine products"
    }
  ]
}
{% endschema %}