Show products from a specific collection in Shopify

specific-products.liquid

<!-- the collection handle we are pulling from is 'new'--->
{% assign collection = collections['new'] %}

{% for product in collection.products | limit: 4 %}
  <!-- the 'product-block' is specific to your theme, it is html for a grid item of a product, could be called product-grid-item, grid-product, etc --->
  {% render 'product-block', product: product %}
  <!-- product --->
{% endfor %}