The game doesn’t offer SSAA, and render scale 200 is the same as 2xSSAA.
Super sampling anti aliasing = rendering at double the resolution then down sampling
Or watch this slide show
Anyway it seems you understand the benefit of SSAA, now you only need to take the step to realizing that SSAA is rendering 4x the pixels (for example 2160p) to display the mathematical average of those pixels (for example 1080p)