Show Admin Menu

Question

I am learning WordPress Plugin development. I need to create a Add New sub-menu like this image:

My code is like below:

public function register_custom_post_type() {
    $supports = ['title'];
    $labels = [
        'name' => __( 'News', 'wpwi' ),
        'singular_name' => __( 'News', 'wpwi' ),
        'name_admin_bar' => __( 'News', 'wpwi' ),
        'add_new' => __( 'Add New', 'wpwi' ),
        'add_new_item' => __( 'Add New News', 'wpwi' ),
        'new_item' => __( 'New News', 'wpwi' ),
        'edit_item' => __( 'Edit News', 'wpwi' ),
        'all_items' => __( 'News', 'wpwi' ),
        'search_items' => __( 'Search News', 'wpwi' ),
        'not_found' => __( 'No News Found.', 'wpwi' ),
    ];

    $args = [
        'public' => true,
        'show_ui' => true,
        'supports' => $supports,
        'labels' => $labels,
        'description' => 'News Information',
        'has_archive' => true,
        'exclude_from_search' => false,
        'show_in_menu' => 'news_info',
    ];

    register_post_type( 'news_info', $args );
}

public function admin_menu() {
    add_menu_page( __( 'News Information', 'wpwi' ), 'News Info', 'manage_options', 'news_info', [$this, 'api_key_page'], 'dashicons-info-outline', 30 );
    add_submenu_page( 'news_info', __( 'News Information', 'wpwi' ), 'API Key', 'manage_options', 'news_info_page', [$this, 'api_key_page'], 0 );
    add_submenu_page( 'news_info', __( 'News Information', 'wpwi' ), 'Add News', 'manage_options', 'news_info', 'call_back_function', 1 );
}

I would like to show Admin Menu like below.

API Key
Add New
News Infos

Answer 1

add_submenu_page() this function used to add submenu in Admin Menu Page. And You will remove submenu from wordpress admin using remove_submenu_page().

add_submenu_page() by default takes 7 parameters.

add_submenu_page( 
      string $parent_slug, 
      string $page_title, 
      string $menu_title, 
      string $capability, 
      string $menu_slug, 
      callable $function = '',
      int $position = null 
)

Write the following code in your functions.php file to create custom post type.

//admin menu callback function

function coupon_register_submenu_page() {

    //Add Offer Configuration Sub Menu   
    add_submenu_page('edit.php?post_type=coupon', 'coupon configuration', 'Coupon Configuration', "manage_options", 'coupon_configuration', 'couponconfiguration', '');

    //Add Deal Configuration Sub Menu
    add_submenu_page('edit.php?post_type=coupon', 'deal configuration', 'Deal Configuration', "manage_options", 'deal_configuration', 'dealconfiguration', '');

    //Add Custom Social Sharing Sub Menu
    add_submenu_page('edit.php?post_type=coupon', 'deal configuration', 'Social Options', "manage_options", 'social-share', 'social_share_page', '');
    
}
add_action('admin_menu', 'coupon_register_submenu_page');

//add submenu page callback function

function couponconfiguration(){
    echo 'Offer Configuration';
    return;
}

function dealconfiguration(){
    echo 'DEAL Configuration';
    return;
}

function social_share_page(){
    echo 'Social Sharing Configuration';
    return;
}