As of now, there is no free demo or trial version of Microsoft Flight Simulator 2020 available. However, you can watch gameplay videos and reviews to get a feel for the game.
: You can download the Xbox App for Windows 10/11 or visit the official Xbox PC page to join. Official Purchase & Download Links microsoft flight simulator 2020 download pc gratis link
This is the "unlimited free" method for dedicated users. As of now, there is no free demo