I imagine it’s not what you want to hear/read, but for freeware, give this a go https://forums.flightsimulator.com/t/msfs-c152-community-v1-0-0-updated-09-10-2021
I know it’s a C152 but it’s similar to the 172 and it’s better than the default aircraft. There’s also an amazing G36 project but it’s not really a Cessna.
There are payware options as well if you want a better aircraft but at the time, no C172 that’s as realistic as the real one.
Can you drag the edges of that window to resize it?
You can do that on the weather/time menu, you can access it before you start your flight or during it, it’s one of the buttons on that bar on top of your screen. If for some reason you can’t change it during flight, change it before you start your flight. You can choose between live weather and a few other options, including clear weather and snow.
I’m not sure as I haven’t tried this, but you can “backup” your game. I have no clue if the installation will recognize it once you try to install it again.
If you bought this on the MS Store, google tells me this is the install location: C:\Users"YourUsername"\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe
If you bought this on Steam, this is my install location: C:\Users\User\AppData\Roaming\Microsoft Flight Simulator