WooCommerce custom emails header

functions.php

<?php // Do not include this if already open! Code goes in theme functions.php.

add_filter( 'woocommerce_email_headers', 'woo_update_emails_header', 10, 2);

function woo_update_emails_header( $headers, $object ) {
    $headers = array();
    $headers[] = 'Content-Type: text/html; charset=UTF-8'; // update the encoding/charset here
  
    return $headers;
}