Global variable of Metaboxes

I am learning WordPress Plugin Development. My Code is like below.

class Admin
{
    
    public function __construct()
    {        
        add_action( 'admin_menu', [$this,'news_meta_boxes'] );
    }

    public function news_meta_boxes()
    {
        add_meta_box('news_settings', 'News Settings', [ $this, 'post_settings_html' ], 'news', 'normal', 'default');
        add_meta_box('display_settings', 'Display Settings', [ $this, 'display_settings_html' ], 'news', 'normal', 'default');
        add_meta_box('style_settings', 'Color Settings', [ $this, 'style_settings_html' ], 'news', 'normal', 'default');
    }
    

    public function post_settings_html($post)
    {
        $stored_meta = get_post_meta($post->ID); // I would like to use it globally as like member variable

        // more code here
    }

    public function display_settings_html($post)
    {
        $stored_meta = get_post_meta($post->ID); // I would like to use it globally as like member variable
        
        // more code here
    }

    public function style_settings_html($post)
    {
        $stored_meta = get_post_meta($post->ID); // I would like to use it globally as like member variable

        // more code here
    }
}

How can I use $stored_meta = get_post_meta($post->ID); globally like member variable ?