How can i update my phone ?

Those devices are very old (5 years (iPhone 6) and 6 years (iPhone 5s) and they both lack the necessary hardware for iOS 13. If you want iOS 13, you need atleast the iPhone 6s.

iOS 13 and iPadOS are compatible with these devices

https://support.apple.com/en-us/HT210327

Neither the iPhone 5s nor 6 can be upgraded to iOS13.