Some modern cars won’t sit for a full month. Too many “keep alive” systems that have to be ready so they are small parasitic drains that all add up to a rather large drain.
Batteries will lose charge over time if they just sit. It is in the nature of lead acid batteries. If the battery is large enough, the starting current low enough, and the temperature low enough, then it can sit for a year or even more.
This car should be able to sit for months and months, at least.