Find the next id in the database

What is the best way to find the next id in the table? For example, a customer is creating a booking number 119 and I want to log it, how would I find that in the same method I'm storing the booking?

See example:

public function createBooking(Request $request)
    {
        $token = uniqid();
        $booking_ref = uniqid();

        $nextId = Booking::find /////// what do here?

        $booking = Booking::create([
            'carNumber' => $request->input('carNumber'),
            'carSize' => $request->input('carSize'),
            'carMake' => $request->input('carMake'),
            'carType' => $request->input('carType'),
            'carColor' => $request->input('carColor'),

            'name' => $request->input('name'),
            'socialId' => $request->input('socialId'),
            'email' => $request->input('email'),
            'phone' => $request->input('phone'),

            'dropOffDate' => $request->input('dropOffDate'),
            'dropOffTime' => $request->input('dropOffTime'),
            'pickUpDate' => $request->input('pickUpDate'),
            'pickUpTime' => $request->input('pickUpTime'),

            'flightNumber' => $request->input('flightNumber'),

            'numberOfDays' => $request->input('numberOfDays'),
            'priceForDays' => $request->input('priceForDays'),

            'paidPrice' => $request->input('paidPrice'),

            'step' => $request->input('step'),

            'reservation_date' => date("Y-m-d H:i:s"),
            'token_expaire_date' => date("Y-m-d H:i:s"),

            'token_korta' => $token,
            'booking_ref' => $booking_ref
        ]);

        $booking->services()->attach($request->input('selectedServicesId'));

        $key = $booking_ref . '-' . $token;

        $dateTimeNow = date("Y-m-d H:i:s");

        Log::channel('slack')->notice('Bókun hefur stofnuð. Kt: '.($booking->socialId).', Netfang: '.($booking->email).', Bókunarnr.: '.$key.', Dags.: '.$dateTimeNow.', Skref: 1');

        if (request()->wantsJson()) {
            return $key;
        }

        return $key;
    }