The iPhone XS Max has a 6.5in (16.5cm) display. The iPhone XS has the same 5.8in-sized component as the original. The iPhone XR's screen is 6.1in but is lower quality.
A new smartwatch was also launched with an added fall-detection function.
There had been concerns that the relatively high £999 entry price of iPhone X would limit its appeal.
The XS Max will become the most expensive handset Apple has sold to date, with its price ranging from £1,099 to £1,449 depending on its amount of storage.
The XS will match the original X's £999-£1,349 cost, while the XR will be £749-£899.