Do you have Instagram? That particular app as well as some others by Meta are particularly power hungry even when you are not using the app. If it is one of those apps, you can check for an update by Meta or uninstall the app to see if the battery problem is solved. There was another update to Instagram just yesterday.
The green battery graph along with the top apps that are consuming the battery seen at Settings > Battery would be helpful to see what is going on with your phone.
Third party reviews do demonstrate the the battery in the iPhone 17 Pro Max does last longer than previous devices, but of course that will depend on the apps installed and as already been suggested a weak cell signal will require more power to maintain a connection to a distant cell tower.