C02 increases the plants photosynthetic rate so it also increases overall growth and yield, but to my knowledge I don’t think wouldn’t make a difference in pest control.
It also allows plants to thrive in a bit hotter environment than with low C02 levels.
Which the insects may love as well…
Also some more details would definitely help, but in flower, I would look into using some beneficial insects to combat any pest issue, and maybe if it gets bad enough where you have buds full of bugs/eggs/webs, depending on what pest you have, I’d consider starting over say if it got so bad that you wouldn’t want to smoke it, then take it as a loss and a lesson, and next run use IPM from the start, and don’t bring in clones from outside gardens as well, which I’ve had to do in the past and take a complete loss of smoke, and just buy my supply again temporarily, when I brought in a dirty clone to try to get new strains going quickly, it really bit me in the ass.
Every garden should have a fairly regular IPM regimen, just in case, as drastic environmental fluctuations can easily cause a PM breakout, or bud rot, and pests are easy to bring in from outside clones, or even soil that was kept outdoors and exposed to insects, etc.
Being a soil grower myself, I use mostly beneficial insects, neem/karanja meal in my soil mix, neem oil, essential oils, a lot like what you would find available in the IPM kits on build a soils website.
That’s just my approach, but I know others will have other methods that may work better for your environment or situation.
Good luck with the pest situation, and happy growing!