Starting next week, Apple Intelligence will be automatically enabled on all supported iPhones, iPads, and Macs as a part of the most recent software update.
If you don't want to use it, you'll have to turn it off manually.

When Apple Intelligence initially appeared in iOS 18.1, it was an optional feature that users could enable. Apple obliged some users to join a waiting list before using it.
However, things have changed with the release of iOS 18.3 and macOS 15.3. Apple Intelligence will now be a default feature on all compatible devices, including the iPhone 15 Pro, Pro Max, iPhone 16 series, and Macs with M1 or newer CPUs.
Apple Intelligence will be activated automatically for anyone setting up a new device or upgrading to the latest software. While the feature offers enhanced capabilities, such as improved Siri interactions and smart suggestions, officially, it's still in beta and may raise concerns for some users.
If you don't want to use Apple Intelligence, navigate to Settings > Apple Intelligence & Siri and turn the toggle off. Once you do, the feature will no longer be active on your device.

It's worth noting that Apple Intelligence is only accessible in certain areas and languages. For supported devices, all processing is handled securely on the device or via Apple's Private Cloud Compute, ensuring data is encrypted and not stored.
While the automatic inclusion of beta capabilities may appear premature to some, Apple is confident in the security and benefits of Apple Intelligence. However, customers who value control over such functions should review their settings after the update.