How to update my iPhone to iOS 18?

It is not available yet. So no, you cannot update to iOS 18.

According to Apple, your iPhone X is too old and will not be compatible.

Therefore, I recommend consider upgrading later this year when the newer models are introduced.

Good luck! 👋🏼😉

You will be able to update your phone......if it is qualified......in 3-4 months when iOS 18 is officially released.

Become a Beta Tester.

But not everything will work right.

Otherwise, you will need to wait like the rest of us for the official release of a verified version.