Updating iOS on iPhone 5c

I have an iPhone 5c. I note the announcement that iPhone 5 models must be updated to iOS 10.3.4 before November 3rd 2019.

The phone is showing its current version as 10.3.3, but when I go to software update it tells me that it is up to date, and confirms the version of 10.3.3.

Does this phone need an update?

How do I update it?

Why is it not offering the 10.3.4 update?

Thanks,

John.