How do I activate apple tv from ipad?

Did you want to start the Apple TV+ subscription? Get Apple TV+ - Apple Support

Are you eligible for the Apple TV+ offer for an extended trial period to Apple TV+?

Then redeem within the first 90 days. Redeem on your new eligible Apple device in the TV app.

Read here how to redeem: Apple TV+ offer - Apple

Read here about the conditions: Apple TV+ offer - Terms and conditions - Apple

Read here if you have trouble redeeming: If you can't redeem your promotion for an Apple subscription - Apple Support

iPad Pro, iPadOS 14

Keep your iPad up-to-date. Update your iPhone, iPad, or iPod touch - Apple Support