The short answer is that is not a free-to-play game, but you can play it without a large upfront purchase by using Xbox Game Pass . If you are looking for a completely free experience, you can explore open-source alternatives like FlightGear or browser-based sims like GeoFS . Exploring Microsoft Flight Simulator for "Free"
While the base game ranges from , there are several legal ways to lower the barrier to entry: Microsoft Flight Simulator free