// Get an instance of the WC_Order object
$order = wc_get_order($order_id);
// Iterating through each WC_Order_Item_Product objects
foreach ($order->get_items() as $item_key => $item_values):
## Using WC_Order_Item methods ##
// Item ID is directly accessible from the $item_key in the foreach loop or
$item_id = $item_values->get_id();
## Using WC_Order_Item_Product methods ##
$item_name = $item_values->get_name(); // Name of the product
$item_type = $item_values->get_type(); // Type of the order item ("line_item")
$product_id = $item_values->get_product_id(); // the Product id
$wc_product = $item_values->get_product(); // the WC_Product object
## Access Order Items data properties (in an array of values) ##
$item_data = $item_values->get_data();
$product_name = $item_data['name'];
$product_id = $item_data['product_id'];
$variation_id = $item_data['variation_id'];
$quantity = $item_data['quantity'];
$tax_class = $item_data['tax_class'];
$line_subtotal = $item_data['subtotal'];
$line_subtotal_tax = $item_data['subtotal_tax'];
$line_total = $item_data['total'];
$line_total_tax = $item_data['total_tax'];
endforeach;