The phrase "headline feature" refers to the main or most important aspect of something. It is similar to the headline of a newspaper article, which captures the main idea or the most significant information about a story. Full definition
This has been rumored and it would be a great headline feature for the phone. (techradar.com)
The big new headline feature on the Note 7 is the iris scanner, which uses a special front - facing camera array to scan your eyes and unlock your phone. (theverge.com)
However, certain headline features like the fingerprint scanner and heart rate monitor are mediocre at best. (smartphone.ninja)