Everything depends on the arrival time of your flight. There are shuttles from Turin airport to Serre Chevalier, which start in the daytime on Saturdays and Sundays almost every hour. The ticket price is about 60-70 EUR per person

If you do not get to it, then you can get to Serre Chevalier as follows: from the airport you need to move to Torino Porta Nuova railway station. Then the train to Souza d'Oulx - the journey time is 1 hour, departure every hour.

Then the Bus Souza d'Oulx - Briançon by route s33, the timetable is here.

The Briançon-Serre-Chevalier segment can be reached by taxi, there is about 15 km, but there is a bus service.

I would recommend using the transfer, the car for the whole journey from Turin airport to the hotel in Serre Chevalier will cost about 250-300 EUR. If the time for the service is 20:00 - 08:00, the extra charge is 25%