How to print Blocks in commerce-product.html.twig
You can use hook_preprocess_commerce_product to load the block and pass the variable to your twig file.

function YOURTHEME_preprocess_commerce_product(array &amp;$variables) {
  $block = \Drupal\block_content\Entity\BlockContent::load(4);
  $variables['custom_block'] = \Drupal::entityTypeManager()-&gt;
    getViewBuilder('block_content')-&gt;view($block);
}


and then in your twig file you will have the {{ custom_block }} variable set.

On a sidenote, this answer helps a lot when trying to programatically load blocks.