It is to stop the mount of emissions. Not for CO2 in your garage. All you have to do is push and hold the START button until a display shows on your dash.
https://gmauthority-com.cdn.ampproject.org/v/s/gmauthority.com/blog/2021/09/heres-how-to-stop-a-gm-vehicle-from-shutting-off-engine-when-parked/amp/?amp_gsa=1&_js_v=a9&usqp=mq331AQKKAFQArABIIACAw%3D%3D#amp_tf=From %1%24s&aoh=16466861833715&referrer=https%3A%2F%2Fwww.google.com&share=https%3A%2F%2Fgmauthority.com%2Fblog%2F2021%2F09%2Fheres-how-to-stop-a-gm-vehicle-from-shutting-off-engine-when-parked%2F
