Add a class retrieved from a sibling field to responsive image
What I'd recommend is to simply preprocess the paragraph, get the "round image" Boolean, and use it to add a class to the paragraph. This should be just enough to style the responsive image accordingly.

/**
 * Implements template_preprocess_paragraph__PARAGRAPH_TYPE.
 */
function MYTHEME_preprocess_paragraph__profile_card(&amp;$variables) {

  // Get paragraph.
  $paragraph = $variables['paragraph'];

  if (!$paragraph-&gt;get('field_rounded_profile_image')-&gt;isEmpty()) {

    // Get Boolean.
    $rounded = $paragraph-&gt; field_rounded_profile_image-&gt;first()-&gt;getValue();

    if ($rounded['value'] == '1') {
      $variables['attributes']['class'][] = 'rounded-image';
    }
  }
}


And then via CSS (Sass) you'd do:

.paragraph-profile-card {
  &amp;.rounded-image {
    .field-profile-image {
      // rounded image styles
      // ...
    }
  }
}