woocommerce/plugins/woocommerce-blocks/docs/examples/checkout-order-processed.md

Checkout Order Processed

// The action callback function.
function my_function_callback( $order ) {
  // Do something with the $order object.
  $order->save();
}

add_action( 'woocommerce_blocks_checkout_order_processed', 'my_function_callback', 10 );