You might want to see this topic of mine which is directly related then:
I’ve just finished testing NVidia Aniso 16x + FS2020 off, and NVidia Aniso Let App Decide + FS2020 16x
Results: the same.
Actually it is a little more complex in FS2020:
Anisotropic is like any other anisotropic filtering, basically using ddx/ddy to compensate for the non-linear along Z axis sampling.
Texture Super Sampling is only for the ground decals (the painted lines yellow, white, red etc… and the fuselage I believe too).
You can get nearly same visuals when siting on the ground with Aniso 4X + Tex.SS 4x4 vs Aniso 16x + Tex.SS 0x0 in practice, but the rendering cost is not the same, because Aniso is hard-wired in the GPU silicon, but Text.SS is FS2020 shader code.
As a matter of fact, prior SU5, I used to reducing stuttering at airports in VR a lot, with Tex.SS 0x0, and I still do with SU5 (but to a lesser extent now), especially on these airports with tons of ground decals.
Of course the more, the merrier. If your GPU supports 16x + 8x8, then go for it!