How to keyframe animate power window opacity or Key output using keyframes

I cant figure this out. I have a simple power window that brightens a spot in my frame. I need the power window opacity or key output to increase at a certain point. The key frame options are only for a handful of variables. I tried DEFOCUS, COLOR CORRECTOR specifically but then I also just keyframes all of them and its not changing.

https://preview.redd.it/fpiuy4u6uldh1.png?width=3730&format=png&auto=webp&s=9cc4c2fe126077b21efeef6b01790d0ce47fe508

I think this is probably pretty simple but I just cant figure it out thanks