Hi,

Add this code to the functions.php of the child theme:

function thegem_woocommerce_output_related_products_args_new($args) {
    $args['posts_per_page'] = 4;
    $args['columns'] = 4;
    return $args;
}
add_filter('woocommerce_output_related_products_args', 'thegem_woocommerce_output_related_products_args_new', 999);