<?php
/**
* Implements hook_token_info().
*/
function customtokens_token_info() {
   $type = [
       'name' => t('Custom Token'),
       'description' => t('Tokens for custom things.'),
   ];
   $node['landingct'] = [
       'name' => t("Research Landing Page"),
       'description' => t('The node\'s Research Landing Page'),
   ];
   return [
       'types' => ['customtoken' => $type],
       'tokens' => ['customtoken' => $node],
   ];
}
/**
* Implements hook_tokens().
*/
function customtokens_tokens($type, $tokens, array $data, array $options, \Drupal\Core\Render\BubbleableMetadata $bubbleable_metadata) {
    $replacements = [];
    $nids = \Drupal::entityQuery('node')->condition('type','research_landing_page')->execute();
    $nodes =  \Drupal\node\Entity\Node::loadMultiple($nids);
    $lid = array_shift(array_keys($nodes));
    $alias = \Drupal::service('path.alias_manager')->getAliasByPath('/node/'.$lid);

    if ($type == 'customtoken' && !empty($data['node'])) {
      foreach ($tokens as $name => $original) {
        switch ($name) {
          case 'landingct':
            $replacements[$original] = $alias;
            break;
        }
      }

    }
   return $replacements;
}