Pluck multidimensional array

Okay, I have User model with:

    public function cars()
    {
        return $this->hasMany(Car::class);
    }

Car model with:

    public function user()
    {
        return $this->belongsTo(User::class);
    }

    public function bookings()
    {
        return $this->hasMany(Booking::class);
    }

Booking Model with:

    public function car()
    {
        return $this->belongsTo(Car::class);
    }

    public function service()
    {
        return $this->belongsTo(Service::class);
    }

Service model with:

    public function bookings()
    {
        return $this->hasMany(Booking::class);
    }

I've menaged to get multidimensional array like

{

    "id": 4,
    "plate": "PNB-238",
    "manufacturer": "Soyat",
    "model": "Yuejin",
    "year": 2005,
    "kilometrage": 269751,
    "hp": 256,
    "cc": 1768,
    "user_id": 2,
    "created_at": "2019-02-11 15:57:24",
    "updated_at": "2019-02-11 15:57:24",
    "bookings": [
        {
            "id": 1,
            "car_id": 4,
            "service_id": 6,
            "start_time": "2019-05-20 23:57:24",
            "end_time": "2019-05-20 23:57:24",
            "created_at": "2019-02-11 15:57:24",
            "updated_at": "2019-02-11 15:57:24",
            "service": {
                "id": 6,
                "name": "ipsa voluptas quia",
                "cost": 8845,
                "time_required": "08:46:00",
                "warranty": 9841,
                "created_at": "2019-02-11 15:57:24",
                "updated_at": "2019-02-11 15:57:24"
            }
        },
        {
            "id": 3,
            "car_id": 4,
            "service_id": 8,
            "start_time": "2019-03-16 22:57:24",
            "end_time": "2019-03-16 22:57:24",
            "created_at": "2019-02-11 15:57:24",
            "updated_at": "2019-02-11 15:57:24",
            "service": {
                "id": 8,
                "name": "molestiae esse voluptatibus",
                "cost": 9646,
                "time_required": "11:40:00",
                "warranty": 6797,
                "created_at": "2019-02-11 15:57:24",
                "updated_at": "2019-02-11 15:57:24"
            }
        }
    ]

},

How I can get one-dimensional array of this. I managed to do that with

        $now = Carbon::now();

        $bookings = Booking::join('cars', 'bookings.car_id', 'cars.id')
            ->join('users', 'cars.user_id', 'users.id')
            ->join('services', 'bookings.service_id', 'services.id')
            ->where('bookings.start_time', '>', $now)
            ->where('users.id', auth()->user()->id)
            ->orderBy('bookings.start_time', 'ASC')
            ->get(['cars.plate', 'bookings.end_time', 'services.name']);

but I need it with

$bookings = auth()->user()->cars()->with('bookings.service')->get();

like: cars.plate | booking.start_time | service.name

Thanks