Are you in the US? If not, you'll need to meet very specific system requirements to access Apple Intelligence features from your iPad.
Here are Apple's published System Requirements:
Apple Intelligence requirements for iPhone, iPad, and Mac
- iPhone 16, iPhone 16 Plus, iPhone 16 Pro, iPhone 16 Pro Max, iPhone 15 Pro, or iPhone 15 Pro Max; any iPad with A17 Pro or M1 and later; Mac with M1 or later
- iOS 18.1, iPadOS 18.1, or macOS Sequoia 15.1
- Device language and Siri language set to a supported language
- 4 GB of storage1
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Supported languages: Apple Intelligence is available in English (US) in most regions around the world. In December, Apple Intelligence will add support for English (Australia), English (Canada), English (Ireland), English (New Zealand), English (South Africa), and English (UK). Over the course of the next year, Apple Intelligence will expand to more languages, like Chinese, English (India), English (Singapore), French, German, Italian, Japanese, Korean, Portuguese, Spanish, Vietnamese, and others.
After you have turned on 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 macOS Sequoia 15.1 on supported Mac models. For iOS 18.1 and iPadOS 18.1, Apple Intelligence will not currently work if you are in the EU and if your Apple Account Country/Region is also in the EU. If traveling outside of the EU, Apple Intelligence will work on your iPhone or iPad if your language and Siri language are set to a supported language.
For China residents: Apple Intelligence will not currently work for supported devices purchased in China mainland. For supported devices purchased outside of 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 the EU or China mainland, previously purchased devices that support Apple Intelligence will be able to activate and use it in that region.
The full System Requirements text can be accessed here:
How to get Apple Intelligence - Apple Support