Adding time of order to Admin email for new order

paste this below code your active theme functions.php file

add_action( 'woocommerce_email_order_details', 'order_date_email_hook', 10, 4);

function order_date_email_hook( $order, $sent_to_admin, $plain_text, $email ){
    if ( $sent_to_admin ) 
    {
        echo '<span>Order Date: '.$order->get_date_created().'</span>';
      }
}