How do I get the field definition of a paragraphs image field
As it mention in comment just use paragraph instead of node.

$fieldDefinition = \Drupal::entityManager()-&gt;getFieldDefinitions('paragraph', 'your_paragraph_type_name');
    foreach ($fieldDefinition as $field_name =&gt; $field_definition) {
      if ($field_definition-&gt;getType() == 'image'){
        $settings    = $field_definition-&gt;getSettings();
        $resolution  = $settings['min_resolution'];
      }
    }