Assuming that you are in a country where the new features of Apple Intelligence and Siri are supported, have you actually enabled Apple Intelligence in iPhone settings?
Settings > Apple Intelligence & Siri > Apple Intelligence - set to ON
How to get Apple Intelligence - Apple Support
Supported languages
Apple Intelligence is available on supported iPhone, iPad and Mac models in Chinese (Simplified), English (Australia, Canada, India, Ireland, New Zealand, Singapore, South Africa, UK and US), French (Belgium, Canada, France, Switzerland), German (Austria, Germany, Switzerland), Italian (Italy, Switzerland), Japanese, Korean, Portuguese (Brazil), Spanish (Chile, Mexico, Spain, US). Apple Intelligence is available on Apple Vision Pro devices set to English (US).
After getting started with Apple Intelligence, it will continue to work when you travel to other regions around the world.
For European Union residents
Apple Intelligence is available with iOS 18.4 and iPadOS 18.4 or later on supported iPhone and iPad models, and with macOS Sequoia 15.1 or later on supported Mac models.
For China residents
Apple Intelligence will not currently work for supported devices purchased in China mainland. For supported devices purchased outside China mainland, Apple Intelligence will not currently work if you are in China mainland and if your Apple Account Country/Region is also in China mainland.
When Apple Intelligence is available in China mainland, previously purchased devices that support Apple Intelligence will be able to activate and use it in that region.
