I get max three days but average two on my 6S running 13.3. I like 13 myself. A welcome change from the iOS 7 look by far. Especially at night. Makes me crave an X or 11 since the bottom bezel kinda doesn't look like it belongs on a 6S; software looks like it wants a seamless bottom.
I like the Pro's of IOS 13 but the con is 2 hours of battery life (for me) instead of the 24 hours.