it depends on what you need it for, but my battery easily lasts me 1-2 days with normal use (theoretically) and with intensive use of social media at the weekend I can easily search for 6-8 hours on god!

Get in touch with Apple support. I once had an update that wasn't installed properly and led to the same problem.

Rather unlikely with normal use.

As long as three navigation apps are not routed and streamed simultaneously, the iPhone is probably defective.

Mine lasts between 24-36 hours. It depends on what the device is doing and your surfing or streaming behaviour. The number of location services activated also affects the battery life. Recommendation: Discharge the battery completely until the device switches off and then fully charge it again. This should always be done. Protects and helps the battery.

It's not normal, maybe something is running in the background and draining the battery