The battery slowly loses its charge when a vehicle sits idle. It should be enough to simply start the car every 3-4 days to prevent battery drain.
If you can, go for a short drive (heading out for essentials?). But even running the vehicle’s engine while going nowhere for 5-10 minutes will boost battery health.
Make sure you do this in an open area. DO NOT do this in a closed environment, such as a garage, as exhaust fumes are toxic.