Date_picke.php

/**
that code is used by code snippet https://wordpress.org/plugins/code-snippets/
 * @snippet       WooCommerce Checkout date picker
 * @author        NCY Design https://wordpress.ncy.design
 * @compatible    WooCommerce 3.7.0
 */
// Register main datepicker jQuery plugin script
add_action( 'wp_enqueue_scripts', 'enabling_date_picker' );
function enabling_date_picker() {

    // Only on front-end and checkout page
    if( is_admin() || ! is_checkout() ) return;

    // Load the datepicker jQuery-ui plugin script
    wp_enqueue_script( 'jquery-ui-datepicker' );
}

// Call datepicker functionality in your custom text field
add_action( 'woocommerce_after_checkout_billing_form', 'display_extra_fields_after_billing_address' , 10, 1 );
function ncydesign_datepicker_field( $checkout ) {

    date_default_timezone_set('America/Los_Angeles');
    $mydateoptions = array('' => __('Select PickupDate', 'woocommerce' ));

    echo '<div id="my_custom_checkout_field">
    <h3>'.__('Delivery Date').'</h3>';

    // YOUR SCRIPT HERE BELOW
    echo '
    <script>
        jQuery(function($){
            $("#datepicker").datepicker({ minDate: 0});
        });
    </script>';

   woocommerce_form_field( 'delivery_date', array(
        'type'          => 'text',
        'class'         => array('my-field-class form-row-wide'),
        'id'            => 'datepicker',
        'required'      => false,
        'label'         => __('Delivery Date'),
        'placeholder'       => __('Select Date'),
        'options'     =>   $mydateoptions
        ),
    $checkout->get_value( 'cylinder_collect_date' ));

    echo '</div>';
}
/**
 * Process the checkout
 **/
add_action('woocommerce_checkout_process', 'my_custom_checkout_field_process');

function my_custom_checkout_field_process() {
    global $woocommerce;

    // Check if set, if its not set add an error.
    if (!$_POST['delivery_date'])
         wc_add_notice( '<strong>Delivery Date</strong> ' . __( 'is a required field.', 'woocommerce' ), 'error' );
}
 /**
 * Update the order meta with custom fields values
 * */
 add_action('woocommerce_checkout_update_order_meta', 'my_custom_checkout_field_update_order_meta');

 function my_custom_checkout_field_update_order_meta($order_id) {

if (!empty($_POST['delivery_date'])) {
    update_post_meta($order_id, 'Delivery Date', sanitize_text_field($_POST['delivery_date']));
}
}