Earlier in June, Apple announced at their Worldwide Developers Conference that they would be offering a "Buy Now, Pay Later" (BNPL) service called Apple Pay Later with iOS 16.
However, even after the iOS update dropped earlier this month, the new feature has since remained absent for iPhone users, with Apple having added a footnote to their iOS 16 webpage specific to the Pay Later service, which states that it will be "coming in a future update for qualifying applicants in the United States for purchases online and in apps on iPhone and iPad".