I am trying to figure out Drupal 8’s $ variables array …

So I have a MYTHEME.theme file, complete with a working MYTHEME_preprocess_field() method (I know it works because I use it for other fields that need customization).

Right now I’m focusing on the title of an article displayed on the front page of my site. I can access it with the following:

if ($  variables['field_name'] == 'title') {     $  title = $  variables['element'][0]['#context']['value'];     // ... } 

What I want to do is replace all instances of ® (the registration mark) with <sup>®</sup>. However, setting this value in the array to something else does not change it on the site.

Is there something I’m missing? A few sources I found said to alter (or add) the ['#markup'] element in the array, but there’s a dearth of information about this online.

How do I change the value of a field? This seems like it should be something basic and easy to do.