how to get product id from order id in woocommerce code example

Example 1: woocommerce get product id

global $product;
$product->get_id();

Example 2: woocommerce order item get product id

foreach ( $items as $item ) {
    $product_name = $item->get_name();
    $product_id = $item->get_product_id();
    $product_variation_id = $item->get_variation_id();
}