Trigger WooCommerce email from WP-CLI

trigger_email.php

<?php

/** 
 * This can be run by wp-cli to trigger an email send. 
 * The email is determined by the action. The one below will trigger the "new order email"
 */
 
WC()->mailer();
$order_id = '260'; // this order needs to exist in your store
$args = array( 'order_id' => $order_id );
do_action_ref_array( 'woocommerce_order_status_pending_to_processing_notification', $args );