Co2

If it is a single tube exhaust system yes. you might be able to convert it into a double tube system if it has a separate intake to remove the heat. most will be on the side with no filter to change. just duct tape a larger tube to that. Make sure its larger so you dont overheat the ac by restricting airflow

What CO2 device you're using? CO2 is heavy and tends to follow gravity in your grow room unless something is pulling it or pushing it out. Most would advise to time your releases of CO2 with shutting down any air exits or exhaust. This CO2 on and Exhaust off timming can obviously bring other issues if not properly adjusted, such as humidity or temperature out of control but that's something you have to check trying. If you need the AC on while CO2 releasing then try to hang it with some safe distance above the CO2 dispenser and shut down any other exhaust or fan. If it's not worth to place CO2 dispenser on your room try the CO2 Tabs. They work.

Reducing air extraction you can keep co2 inside the tent 💪 good luck

Nope but you can rise the supplement or use recycle function, if available, to diminish dispersion.

But is it possible to reduce the escape of gas?

Of course.