I want to know if iPhone 11 can have iOS15.5

If your iPhone 11 is currently on a version lower than iOS 15 and you want to update it, you cannot update to iOS 15.5. You can ONLY update to the current iOS version, which is 18.3. And if you really haven't updated your iPhone in several years, you'll need to update it using a computer. See how for either Windows or Mac:

Update your iPhone, iPad, or iPod touch with the Finder - Apple Support

Update your iPhone, iPad, or iPod touch with iTunes - Apple Support

Yes, but if it's not already running that version, it can't be put on there; Apple doesn't allow it to be updated to a version older than the current one for any given model.

(258560)

Niel wrote:

Yes, but if it's not already running that version, it can't be put on there; Apple doesn't allow it to be updated to a version older than the current one for any given model.

There can be exceptions right after a new version of iOS comes out. This is what my iPhone offered in the way of updates in September 2024, a few days after iOS 18 came out. (I was running iOS 16 at the time.)

These are the exceptions that prove the rule. If I was still running iOS 16 now, I'm sure I wouldn't get the option of updating only as far as iOS 17.

The iPhone 11 is – or was – compatible with anything from iOS 13 through iOS 18.

As a rule, Apple does not let you pick and choose intermediate versions. So if your iPhone 11 is running iOS 14 now, as your tag line suggests, your options are to either stay on iOS 14, or update to iOS 18. The windows during which you could have updated to iOS 15, 16, and 17 have passed.

Yes, if it is already installed as the current version. No, if it is not.

To check for an update on your phone......Tap Settings > General> Software Update