How to update iPhone 5s iOS to latest version?

kawsar294 wrote:

Ios 18

No iOS 18 for the iPhone 5s – ever. That phone does not have the hardware needed to run it.

If you want to run iOS 18, buy a compatible phone.

iPhone models compatible with iOS 18 - Apple Support

I believe that only the iPhone 12 series and later support 5G cellular networks, and only the iPhone 15 Pro, 15 Pro Max, and 16 series phones will support Apple Intelligence.

If you are tempted to buy a used phone to "save money", read

The All Too Common SAD Reality of Buying a Used iPad/iPhone – Apple Community

so you know what to look for to reduce the chances of getting an Activation Locked (and possibly stolen "brick").

An iPhone 5s, iPhone 6, or iPhone 6 Plus isn't capable of 13 or above; they require at least 2GB of RAM. To install 12.5.7, use a computer or the Software Update function in Settings.

(256104)

iOS 12.5.7 was the last and final update for the iPhone 5s. No more updates are available.

kawsar294 wrote:

Ios 18

NO. Not remotely possible as you've been told. iOS 12.5.7 is as far as a 5s can be updated to.

The iPhone 5s originally shipped with iOS 7. You can update it to the latest release of iOS 12.

You cannot update it to iOS 13 or later – let alone to iOS 18.