Hello, Douglas1952!
iOS 18.2’s does have some new features other than Apple Intelligence (mostly slight improvements to Photos). On the Apple Intelligence side of things, though, I’m afraid you’re out of luck.
Apple Intelligence needs a lot of performance to run, and also a lot of bandwidth. It needs at least 8 gigs of RAM, 6 CPU cores, and 16 Neural Engine cores. So even if your iPhone 11 was brand new, it would need to match all of those specs to run it. Unfortunately, it doesn’t. You would need one of the compatible devices.

Learn more on the Apple Intelligence website.
I hope this helps!