Show PrettyPrint JSON in Slim3

I am creating a restful api with the framework Slim3 the data is returned to me with json, but to debug I like more to show the answer with a nicer format.

in% pure co_de I do it using

json_encode($datos, JSON_PRETTY_PRINT);

I have the following

$app->get('/ads', function ($request, $response, $args) {
    $db = $this->get('db');
    $datos = $db->get('ads');
    return $this->response->withJson($datos);
});