doubt regarding apple tv subscription

If you qualify, and if you did as described in the guide, and you still do not get to see the year offer, then contact Apple Support. They can assist in getting you the service, if needed using activation codes.

Yes. With a new purchase of your iPhone 11, Apple TV+ is free for one year.

You can check you eligibility on the Apple TV+ website.

https://www.apple.com/apple-tv-plus/

Was the iPhone purchased new or used?

When was the iPhone purchased?

Then it is best to contact Apple support, as advised above.