Add a custom field and email it to below product name

woorommerce-customfield-and-email.php

<?php
/**
 * Display the custom text field
 * @since 1.0.0
 */
function cfwc_create_custom_field() {
 $args = array(
 'id' => 'custom_text_field_title',
 'label' => __( 'Product Name In Thai', 'cfwc' ),
 'class' => 'cfwc-custom-field',
 'desc_tip' => false,
 'description' => __( '', 'ctwc' ),
 );
 woocommerce_wp_text_input( $args );
}
add_action( 'woocommerce_product_options_general_product_data', 'cfwc_create_custom_field' );
/**
 * Save the custom field
 * @since 1.0.0
 */
function cfwc_save_custom_field( $post_id ) {
 $product = wc_get_product( $post_id );
 $title = isset( $_POST['custom_text_field_title'] ) ? $_POST['custom_text_field_title'] : '';
 $product->update_meta_data( 'custom_text_field_title', sanitize_text_field( $title ) );
 $product->save();
}
add_action( 'woocommerce_process_product_meta', 'cfwc_save_custom_field' );

// Setting the email_is as a global variable
add_action('woocommerce_email_before_order_table', 'the_email_id_as_a_global', 1, 4);
function the_email_id_as_a_global($order, $sent_to_admin, $plain_text, $email ){
    $GLOBALS['email_id_str'] = $email->id;
}

// Displaying product description in new email notifications
add_action( 'woocommerce_order_item_meta_end', 'product_description_in_new_email_notification', 10, 4 );
function product_description_in_new_email_notification( $item_id, $item, $order = null, $plain_text = false ){

    // Getting the email ID global variable
    $refNameGlobalsVar = $GLOBALS;
    $email_id = $refNameGlobalsVar['email_id_str'];

    // If empty email ID we exit
    if(empty($email_id)) return;

    // Only for "New Order email notification"
    if ( 'new_order' == $email_id ) {

        if( version_compare( WC_VERSION, '3.0', '<' ) ) { 
            $product_id = $item['product_id']; // Get The product ID (for simple products)
            $product = wc_get_product($item['product_id']); 
        } else {
            $product = $item->get_product();

            if( $product->is_type('variation') ) {
                $product = wc_get_product( $item->get_product_id() );
            }
        }

        // Get the Product description (WC version compatibility)
        if ( method_exists( $item['product'], 'get_description' ) ) {
            $thai_name = $product->get_meta( 'custom_text_field_title' ); // for WC 3.0+ (new)
        } else {
            $thai_name = $product->get_meta( 'custom_text_field_title' ); // for WC 2.6.x or older
        }

        // Display the product description
        echo '<br><div class="product-description">Thai Name: ' . $thai_name . '</div>';
    }
}