除了默认支持中包含的内容之外，如何将特定字段添加到自定义帖子类型？

I've made a custom post type and registered it. I need some more fields for this post type, and would like to add 2 more with the specific keys that will load anytime a new post is made (IE like another excerpt field, but it will say Title/position). I'm not sure how to do this, and would like to avoid plugins. Any help would be greatly appreciated.

    $labels = array(
      'name'                  => _x('Executive', 'post type general name '),
      'singular'              => _x('Executive', 'post type singular name'),
      'add_new'               => _x('Add new', 'text_domain'),
          'add_new_item'          => __( 'Add Executive', 'text_domain' ),
          'name_admin_bar'        => __( 'Staff', 'text_domain' ),
          'archives'              => __( 'Staff Archives', 'text_domain' ),
          'parent_item_colon'     => __( 'Parent Item:', 'text_domain' ),
          'all_items'             => __( 'All Exectives', 'text_domain' ),
          'new_item'              => __( 'New Item', 'text_domain' ),
          'edit_item'             => __( 'Edit Item', 'text_domain' ),
          'update_item'           => __( 'Update Item', 'text_domain' ),
          'view_item'             => __( 'View Item', 'text_domain' ),
          'search_items'          => __( 'Search Item', 'text_domain' ),
          'not_found'             => __( 'Not found', 'text_domain' ),
          'not_found_in_trash'    => __( 'Not found in Trash', 'text_domain' ),
          'featured_image'        => __( 'Featured Image', 'text_domain' ),
          'set_featured_image'    => __( 'Set featured image', 'text_domain' ),
          'remove_featured_image' => __( 'Remove featured image', 'text_domain' ),
          'use_featured_image'    => __( 'Use as featured image', 'text_domain' ),
          'insert_into_item'      => __( 'Insert into item', 'text_domain' ),
          'uploaded_to_this_item' => __( 'Uploaded to this item', 'text_domain' ),
          'items_list'            => __( 'Items list', 'text_domain' ),
          'items_list_navigation' => __( 'Items list navigation', 'text_domain' ),
      'filter_items_list'     => __( 'Filter items list', 'text_domain' ),
      'menu_name'             => __( 'Executives', 'text_domain' ),    
    );
    $args = array(
      'label'                 => __( 'Executive', 'text_domain' ),
      'description'           => __( 'Executive Team', 'text_domain' ),
      'labels'                => $labels,
      'supports'              => array( 'title', 'author','name','excerpt','thumbnail', ),
      'hierarchical'          => false,
      'public'                => true,
      'show_ui'               => true,
      'show_in_menu'          => true,
      'menu_position'         => 5,
      'show_in_admin_bar'     => true,
      'show_in_nav_menus'     => false,
      'can_export'            => true,
      'has_archive'           => true,
      'exclude_from_search'   => false,
      'publicly_queryable'    => true,
      'rewrite'               => false,
      'capability_type'       => 'page',
    );
    register_post_type('Executives', $args);
  }

  add_action('init', 'custom_post_executive');

You need to register a custom meta box with a callback that will render the HTML. You can read more about it here: https://developer.wordpress.org/plugins/metadata/custom-meta-boxes/

I would also recommend looking at the plugin Advanced Custom Fields (ACF) as they make creating meta fields trivial.

function wporg_add_custom_box()
{
    $screens = ['post', 'wporg_cpt'];
    foreach ($screens as $screen) {
        add_meta_box(
            'wporg_box_id',           // Unique ID
            'Custom Meta Box Title',  // Box title
            'wporg_custom_box_html',  // Content callback, must be of type callable
            $screen                   // Post type
        );
    }
}
add_action('add_meta_boxes', 'wporg_add_custom_box');

function wporg_custom_box_html($post)
{
    ?>
    <label for="wporg_field">Description for this field</label>
    <select name="wporg_field" id="wporg_field" class="postbox">
        <option value="">Select something...</option>
        <option value="something">Something</option>
        <option value="else">Else</option>
    </select>
    <?php
}