How to use GPT-4 in Q&A

Question

Request to Weaviate Q&A service:

$weaviate = new Weaviate('http://weaviate:8080/v1/', '');
    $res = $weaviate->graphql()->get('{
Get {
  '.self::$weaviateClass.' (
    ask: {
      question: "'.$request->q.'",
      properties: ["content"]
    },
    limit: 1
  ) {
    title
    _additional {
      answer {
        hasAnswer
        property
        result
        startPosition
        endPosition
      }
    }
  }
}
  }');

dd($res);

How can I use GPT-4-32k or GPT-4 ? Cant find any docs or examples for configuration.