add-delivery-date-on-order-received-page.php

<?php

add_filter( 'woocommerce_order_details_after_order_table', 'add_delivery_date_to_order_received_page', 10 , 1 );

function add_delivery_date_to_order_received_page ( $order ) {
	if( version_compare( get_option( 'woocommerce_version' ), '3.0.0', ">=" ) ) {            
        $order_id = $order->get_id();
    } else {
        $order_id = $order->id;
    }

    $delivery_date = get_post_meta( $order_id, '_delivery_date', true );
    
    if ( '' != $delivery_date ) {
    	echo '<p><strong>' . __( 'Delivery Date', 'add_extra_fields' ) . ':</strong> ' . $delivery_date;
	}
}