Adding a link to an image Is there a module or a way in core to have an Image field be a clickable link to a URL that is either entered as an additional setting for the Image field or can be pulled from another field that stores that URL.

This https://www.drupal.org/project/linked_field looks like what I want, but there doesn't seem to be a token that I can use that will do what I want.  

This also looks exactly like I want but it's for D7. https://www.drupal.org/project/linkimagefield 

I'm using this for a Custom Field Type
If you are already building a custom field type, you could add properties for the link to your field:

class MyLinkField extends FieldItemBase {

  public static function propertyDefinitions(StorageDefinition $storage) {
    ...  
    $properties['title'] = DataDefinition::create('string')
      -&gt;setLabel(t('Title'));
    $properties['url'] = DataDefinition::create('string')
      -&gt;setLabel(t('URL'));
  }


and use it in the field formatter:

class MyLinkFieldFormatter extends FormatterBase {

  public function viewElements(FieldItemListInterface $items, $langcode) {
    $elements = [];
    foreach ($items as $delta =&gt; $item) {
      $elements[$delta] = [
        '#type' =&gt; 'link', 
        '#title' =&gt; $item-&gt;title,
        '#url' =&gt; Url::fromUri($item-&gt;url),
      ];
    }
  return $elements;
  }