add_action( 'wp', 'add_product_to_cart_on_page_id_load' ); function add_product_to_cart_on_page_id_load() { // product ID to add to cart $product_id = 21874; // page ID to target if ( is_page( 19473 ) ) { WC()->cart->empty_cart(); WC()->cart->add_to_cart( $product_id ); } }