I tried to find it online but I couldn't. I'd like to know recommended top cap torque too.
If you cannot find an actual torque spec for the compression plug, you can probably “rough it.” The purpose of the compression plug is two things: provide a fixture that the top cap bolt can draw against (to preload the headset bearings), and to support the inside of the carbon steerer against the clamping force of the stem bolts.
As long as the plug is not loose, it will provide the support needed, so that is not a critical torque. However, the plug needs to be tight enough to not slide when the top cap is adjusted AND to be tight enough to not loosen due to vibration while riding.
One additional note, on a carbon steerer it's possible to overtighten and expand the plug so that it slightly bulges the steerer, and then that may cause the headset to come out of adjustment after you think it's OK because the stem later moves slightly due to the bulge. Just a tip in case you have the headset adjusted properly but then keep finding it goes out of adjustment for seemingly no reason.
A more generalized search for compression plug torque listed 8 N-m for a 1-1/8” carbon steerer. I also found another source that mentions 8-9 N-m. So there are some ballpark-numbers that you can get you close.