size_tables

function mymodule_preprocess_commerce_product(&$variables)
{
    $product = $variables['elements']['#commerce_product'];

    // get products taxonomy terms ids
    $pr_brand_id = $product->get('field_brand')->target_id;
    $pr_category_id = $product->get('field_product_categories')->target_id;

    // get nid of size table (depends on category and brand)
    $query = \Drupal::entityQuery('node')
        ->condition('type', 'size_table')
        ->condition('field_brands', $pr_brand_id)
        ->condition('field_categories', $pr_category_id);
    $nids = $query->execute();

    // set variable with table's render
    if (count($nids)) {
        $nid = reset($nids);
        $node = \Drupal::entityTypeManager()->getStorage('node')->load($nid);
        $view = $node->body->view('default');
        $variables['size_table'] = render($view);
    }
}