How to see curl output?

I have a command class that is sending data to an external site and I want to validate the output from the curl request. So it's not my endpoint that I can test with a curl -o command. What options do I have to execute the class and see that the data is actually getting generated for $request_data below?

I am doing this because my logging isn't generating an error or confirmation so I need to see where this command is failing.

public function handle()
    {
        Log::info('Attempting to post deliveries');
        $users = User::all();

        foreach ($users as $user)
        {
            Auth::loginUsingId($user->id);

            $getswift_key = auth()->user()->getMerchantGetswiftKey();

            if (is_null($getswift_key))
            {
                Log::info("getswift order sync: this merchant ".auth()->user()->email. " not have the getswift key");
                continue;
            }

            $order_headers = OrderHeader::query()->where(function ($q){
                $q->whereNull('getswift_status')->orWhere('getswift_status' , OrderHeader::DELIVERY_NEW);
            })->orderByDesc('id')->get();

            foreach ($order_headers as $order_header)
            {
                if (\Carbon\Carbon::parse($order_header->creation_date)->lessThan(Carbon::now()->addMonth()))
                    continue;

                $url = config('getswift.base_url').config('getswift.deliveries');

                $request_data = $this->mappingGetswiftFeilds($order_header , $getswift_key);

                list($response , $httpcode) = ApiRequest::curlRequest($url , $request_data);

                echo "response code ". $httpcode ." ";
                if ($httpcode != 200 && isset($response->message))
                {
                    Log::error('getswift order sync: order_number: '.$order_header->order_number.' -----message:---- '.$response->message);
                    continue;
                }

                $order_header->getswift_status = OrderHeader::DELIVERY_ADDED;

                if ($order_header->save())
                {
                    Log::info('getswift order sync: order_number: '.$order_header->order_number.' -----message:---- : posted successfully');
                }

            }

            Auth::logout();
        }

    }