How to update my 5s iso 14

You cannot. The iPhone 5s lacks the hardware, CPU and RAM to run anything beyond iOS 12.5.7. It cannot be updated past that. It's a 10 year old device at this point.

Sorry, but this is not possible.

iOS 12.7.5 is as far as the iPhone 5s can go.

If you want to run higher systems.....you need a new phone.