This function will return formatted HTML to display box dimensions and weights for multibox and non-multibox products

multibox_display_box_dimensions.php

<?php

function get_multibox_dimension_output( $product_id = false ) {
  $product = wc_get_product( $product_id );
  if( !$product ) {
    return;
  }
  
  $output = '';
  $boxes = get_post_meta( $product->ID, '_wc-multibox-additional-boxes', true );
  if( $boxes ) {
    var $i = 1;
    foreach( $boxes as $box ) {
      $dimensions = wc_format_dimensions( $box );
      $weight = wc_format_weight( $box['weight'] );
      $output .= '<div class="product-meta"><span class="product-meta-label">Box ' . $i . 'Dimensions: </span>' . $dimensions . '</div>';
      $output .= '<div class="product-meta"><span class="product-meta-label">Box ' . $i . 'Weight: </span>' . $weight . '</div>';
      $i++;
    }
  } else {
    $dimensions = wc_format_dimensions( $product->get_dimensions( false ) );
    $weight = wc_format_weight( $product->get_weight() );
    if ( $product->has_dimensions() ) {
      $output .= '<div class="product-meta"><span class="product-meta-label">Dimensions: </span>' . $dimensions . '</div>';
      $output .= '<div class="product-meta"><span class="product-meta-label">Weight: </span>' . $weight . '</div>';
    }
  }
  return $output;
}