Dropdown Toggle Split in Bootstrap Navwalker WordPress

I faced same issue in my theme and I have saw your theme file to be sure from few things:

1. you didn’t have the Navwalker file in your theme. (Navwalker.php)
2. Navwalker doesn’t need any js file.
3. you need to search for clean copy of Navwalker which allow (Multiple Levels) as you asked.

the solution:
use this copy: craftnce-agency-wordpress-theme

1. Just copy the nav walker code from here and make a file in your project and paste it there, e.g: in css folder file name (nacwalker.php)
2. go your function file in your theme and add this

require_once get_template_directory() . '/css/nacwalker.php';

add this code in your header:

wp_nav_menu(array(
      'theme_location'            =>  'primary',
      'menu_class'                =>  '',
      'menu-container'            =>  'false',
      'fallback_cb'               => '__return_false',
      'items_wrap'                => '<ul id="%1$s" class="navbar-nav ms-auto mb-2 mb-lg-0 text-sm %2$s">%3$s</ul>',
      'depth'                     => 2,
      'walker'                    => new craftnce_wp_nav_menu_walker(),
  ));

then you are ready. no need to any js file. and the styling is easy.