Unable to get my ContentEntity base field definition to appear as checkboxes
Try with options_buttons because this is the ID if the OptionsButtonsWidget widget.

$fields['content_display'] = BaseFieldDefinition::create('list_integer')
  -&gt;setDisplayOptions('form', array(
    'type' =&gt; 'options_buttons',
    'weight' =&gt; -4,
  ))
  -&gt;setSetting('allowed_values', $values)
  -&gt;setDisplayConfigurable('form', TRUE);