Im trying to get my head around this.

Is this accurate?

Once the signal hits the compression threshold,
the output level will follow the designated compression curve...

Suppose we had a compression ratio of 2:1,
When the input increases 10dB;
The output will yield only 5db more gain.
This can be thought of as Input to Output Gain.
We can then use Make-Up or Output Gain
to compensate for the dynamics processing.