Make nav default to dropdown links optional

Not sure that my default boolean for is_dropdown is a good implementation. Is there a better way to set default to true and ensure only a boolean is accepted? My twig-fu is lacking a little.

For those wishing to know how to target menus within a region, this may be helpful:

/**
 * Implements hook_theme_suggestions_HOOK_alter().
 */
function my_radix_preprocess_block(&$variables) {
  // Add the block ID as custom attribute to block content, this will be used
  // for menu template suggestions.
  $variables['content']['#attributes']['block'] = $variables['elements']['#id'];
}

/**
 * Implements hook_theme_suggestions_HOOK_alter().
 */
function my_radix_theme_suggestions_menu_alter(array &$suggestions, array $variables) {
  $menu_name = $variables['menu_name'];
  if (isset($variables['attributes']['block'])) {
    $block = \Drupal\block\Entity\Block::load($variables['attributes']['block']);
    $region = $block->getRegion();
    $suggestions[] = 'menu__' . $region . '__' . $menu_name;
  }
}

With the above, I would be able to target a the main menu within the content region, and specify that it not be dropdown links.

{#
/**
 * Template for the main menu within the content region.
 * @file menu--content--main.html.twig
 */
#}
{% include '@radix/nav/nav.twig' with {
  is_dropdown: false,
  alignment: 'vertical'
} %}