Maybe this will show a comparison on battery life of the Jolla C and the XPeria X.

While my phone number hasn't been transferred from my old to my new operator, I carry the Jolla C around in my backpack only for SMS. The XPeria X is my main phone and phone calls to the Jolla C are redirected to the XPeria X.
On a day without touching the Jolla C at all, and moderate use of the XPeria X, I left the house in the morning with both fully charged, and returned home jn the evening with both at 70% of charge remaining.