The file is .gltf and in case of Store directories the C-172 can be found at
Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\Packages\Official\OneStore\Asobo-aircraft-c172sp-classic\SimObjects\Airplanes\Asobo_C172sp_classic\model
… not sure if it can be decoded, it may be compressed or encrypted, because it is Asobo/MS material belonging to the MSFS base setup.