Upsell @ Thank-you Page

 /**

 * @snippet       Upsell @ Thank-you Page

 * @how-to        Get CustomizeWoo.com FREE

 * @sourcecode    https://businessbloomer.com/?p=111758

 * @author        Rodolfo Melogli

 * @compatible    WooCommerce 3.5.4

 * @donate $9     https://businessbloomer.com/bloomer-armada/

 */

 

add_action( 'woocommerce_thankyou', 'bbloomer_thankyou_upsell', 5 );

  

function bbloomer_thankyou_upsell() {

echo '<h2>Customers also bought...</h2>';

echo do_shortcode( '[products limit="3" columns="3" orderby="popularity" on_sale="true" ]' );

}