Take from AMD.
When using FidelityFX Super Resolution (FSR) at native resolution, the render resolution is lower than the output resolution, but not by the same amount as when using a scaling setting like 0.5x. FSR, essentially an upscaling technology, renders at a lower resolution to improve performance and then uses its algorithm to upscale the image to the native resolution, which is the resolution displayed on the monitor. The amount of downscaling depends on the quality setting chosen (e.g., Ultra Quality, Quality, Balanced, Performance, Ultra Performance).
thst is lethally what FSR and DLSS dose, that how it dose it... unless use frame gen