Not sure if it qualifies and it was very crude graphically, but I think F-18 Hornet on the Atari 7800 might count?
You can see that the aircraft carrier you land on appears to be made of polys...
https://youtu.be/gIj3MIzfEBA?t=504
And here another example where you can see the buildings are made up of simple polys etc. Again, while that game certaintly doesn't play like an actual flight sim, I remember being pretty impressed with its graphics at the time in the late 80s when I bought it and played it on my 7800.
https://youtu.be/gIj3MIzfEBA?t=1042