controller

<?php

namespace Drupal\layout_builder_collapse_categories\Routing;

use Drupal\Core\Routing\RoutingEvents;
use Drupal\Core\Routing\RouteSubscriberBase;
use Symfony\Component\Routing\RouteCollection;
use Drupal\layout_builder_collapse_categories\Controller\ChooseBlockController;

/**
 * Override the controller for layout_builder.move_block.
 */
class RouteSubscriber extends RouteSubscriberBase {

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() {
    $events[RoutingEvents::ALTER] = ['onAlterRoutes', -1000];
    return $events;
  }

  /**
   * {@inheritdoc}
   */
  public function alterRoutes(RouteCollection $collection) {
    // Add a decorator for the choose_block conroller
    if ($route = $collection->get('layout_builder.choose_block')) {
      $defaults = $route->getDefaults();
      $route->setOption('original_controller', substr($defaults['_controller'], 0, strpos($defaults['_controller'], '::')));
      $defaults['_controller'] = ChooseBlockController::class . '::build';
      $route->setDefaults($defaults);
    }

  }
}

<?php

namespace Drupal\layout_builder_collapse_categories\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\layout_builder\SectionStorageInterface;
use Drupal\Core\Controller\ControllerResolverInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;

class ChooseBlockController extends ControllerBase {


  /**
   * The original ChooseBlockController
   *
   * @var \Drupal\layout_builder\Controller\ChooseBlockController $originalController
   */
  protected $originalController;

  /**
   * @param \Drupal\Core\Controller\ControllerResolverInterface $controller_resolver
   */
  public function __construct(ControllerResolverInterface $controller_resolver, RouteMatchInterface $route_match) {
    $original_controller_class = $route_match->getRouteObject()->getOption('original_controller');
    $this->originalController = $controller_resolver->getControllerFromDefinition($original_controller_class);
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static(
      $container->get('controller_resolver'),
      $container->get('current_route_match')
    );
  }

  public function build(SectionStorageInterface $section_storage, $delta, $region) {
    $build = $this->originalController->build($section_storage, $delta, $region);

    foreach ($build['block_categories'] as &$category) {
      if (isset($category['#open'])) {
        $category['#open'] = FALSE;
      }
      
    }

    return $build;
  }

}

    $menu_name = 'my_custom_menu_machine_name';
  
    $menu_tree = \Drupal::menuTree();
    // Build the typical default set of menu tree parameters.
    $parameters = $menu_tree->getCurrentRouteMenuTreeParameters($menu_name);
    // Load the tree based on this set of parameters.
    $tree = $menu_tree->load($menu_name, $parameters);
    // Transform the tree using the manipulators you want.
    $manipulators = [
      // Only show links that are accessible for the current user.
      ['callable' => 'menu.default_tree_manipulators:checkAccess'],
      // Use the default sorting of menu links.
      ['callable' => 'menu.default_tree_manipulators:generateIndexAndSort'],
    ];
    
    $tree = $menu_tree->transform($tree, $manipulators);

    $menu = $menu_tree->build($tree);

     // Set theme for custom styling.
    $menu['#theme'] = 'my_custom_theme';