Drupal 8 Title tag - head-placeholder
I found a way but I'm not sure if it's ideal:

function THEME_preprocess_html(&amp;$variables) {
  $variables['head_title']['title'] = 'title here';
}


Logic can be added for each page:

$path = $current_path = \Drupal::service('path.current')-&gt;getPath();
if ($path === '...')


Then, in html.html.twig:

&lt;title&gt;{{ head_title.title }}&lt;/title&gt;


instead of 

&lt;title&gt;{{ head_title|safe_join(' | ') }}&lt;/title&gt;