While it doesn't affect the sound profile like a normal EQ, it does affect the dynamics, depending on how you shape it. Listen for pumping in the frequency ranges you affect.
I tried shapes of all kinds, even extreme ones, no difference.
I don't understand why.
You expect sound to change? it will not, for that regular EQ is used. As others said, but i'll put it simple to you, for example, if you want AGC to react less to bass - you remove some amount of bass in that SC EQ.
Try this, Reset Sidechain EQ, Play some 80Hz sine tone, give some range in AGC, then try to tune bass on SidechainEQ - watch what AGC is doing.