Here we are going to fetch similar blog by blog node id, so inside .theme file
( in theme root folder) you can add below code and fetch similar blog by “field_blog_tags” field in drupal 8
Drupal 8 Query to get similar blog post
$valuesTags=$variables['node']->get('field_blog_tags')->getValue(); foreach($valuesTags as $key=>$value) { $smilarprd[]=$value['target_id']; } $nids = \Drupal::entityQuery('node')->condition('type', 'blog_post')->condition('field_blog_tags', $smilarprd,'IN')->condition('nid', $Nid, '!=')->range(0, 3)->execute(); $RelatedBlog = \Drupal\node\Entity\Node::loadMultiple($nids); $variables['RelatedBlog'] = $RelatedBlog;