It will vary greatly with the watchface and whether you use wifi (weather, ntp, etc). In the current implementation it will do a full connect every minute so there's room for easy improvement. With wifi I get about 48h out of it.

With my custom watchface I built, I sync ntp and weather every hour. I get about 100 hours of battery from it (4+ days).

The ESP32 is known for being cheap and featureful. The downside is that some functionality is implemented in software which results in lower battery life.