That all depends on the power reserve feature. It sounds fancy, but in reality, it’s just the mainspring and hairspring in the internal components of the watch, and how much tension they’re able to safely hold, while it gets dispersed throughout your watch.
That being said, you generally have to trust whatever the sales page or brand states when it comes to your power reserve time. If you get your watch, and it feels like that reserve is longer or shorter, put it in your winder, and time it to figure out the longevity of your reserve.