Could someone give me a good explanation of when and how to do upscaling please?

I was getting 30’ish fps with 3080ti / 8kx / 100 MSFS TAA and it wasn’t “blurry” but i suppose we all have different ideas on what’s acceptable visually, it’ll never be 4k monitor sharpness. Have you got parallel projections disabled in pitool? What are the Quality and fov settings set to in pitool?