Is there any way to get Apple Intelligence on iPhone 11

No. Currently its slated for iPhone 15 Pro and 15 Pro Max only. (and likely on any new iPhones released after the iPhone 15 Pros)

click here ➜ Apple Intelligence Overview - Apple.com

None of us can predict the future …

… but it’s not going to be supported in iOS 18.

iOS 18 Preview - Apple

Sorry, no. Not enough processing power.

You will need an iPhone 15 or iPhone 15 Pro Max

Nope.