How the output power changes by varying the capacitor connected in series with gate

Hi, I have connected a capacitor (C) in series with the gate of a mosfet(M, let's say a CS amplifier). It's value (180 fF) is not too high like a blocking capacitor. How does increasing or decreasing this value change the output power and lower(input) cut-off frequencies?.

My analysis is like If the C value is decreased, the Vgs of M decreased because of capacitive division. Current swing decreases and hence output power decreases. The lower cut-off frequency is also increases because the over capacitance at the input is decreased. Exactly the opposite happen when the C value is increased. Thanks

Can you understand power correctly ?
Show me your definition of input power.

You have to learn difference between voltage and power correctly, before EDA Tool Play.

A capacitor placed in series with the gate of a MOSFET could change the input impedance matching of the transistor, so the gain will change, and the output power will change.

Capacitive input impedance of the MOSFET is a simplified assumption. The actual input impedance is complex and can be, depending on the operation frequency, transistor and output circuit parameters, quite different from pure capacitive.