javascript – Hi, would anybody know what the file name must be for adding html code to a child theme. for example, must the file be custom.php or custom.js

function my_scripts_method() {
wp_enqueue_script(
      'custom-script',
      get_stylesheet_directory_uri() . "/js/custom_script.js 
      array( 'query' ),'',true );
     
   
}
add_action( 'wp_enqueue_scripts', 'my_custom_script.js' );

Ive tried putting this code in functions.php and header.php to call the javascript. doesn’t work

The countdown javascript animation is in a file named custom_script.js in a folder named js, which is in the child theme folder named wpbdemo.
The animation also had css and html, but that is working I think, as the countdown template is showing, its just not doing any movement. So, I think its the javascript code not working.
The css is in style.css file and the html is in footer.php.