That helped propel Apple to become the world's first company with a market capitalisation above $1tn (£768bn).
However, China's Huawei still managed to overtake it in terms of overall smartphone market share in the April-to-June quarter, putting Apple into third place.
"Huawei was able to overtake it because Apple is not playing in the mid and low ends of the market," commented Francisco Jeronimo from IDC.
"But Apple is very well positioned in the premium segment, and we don't expect that to change over the next 18 months."
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.
Apple highlighted that the iPhone XS Max's display was significantly larger than the 5.5in display of the old iPhone 8 Plus despite the two handsets being similar in size.
"Even if the screen on the iPhone X last year was larger some people who were on the Plus models missed the feel of a larger device which is exactly what the Max is addressing," said Carolina Milanesi, an analyst at the consultancy Creative Strategies.
The iPhone XR also has a bigger screen but uses LCD (liquid crystal display) rather than the OLED (organic light-emitting diode) technology found in the more expensive models. This will mean black appears less deep and its colours appear to have less contrast.
In addition, its chassis is made from aluminium rather than steel, which means it is likely to be less damage-resistant. However, unlike the more expensive models it comes in six different colours.
Analysts suggest the wider range may help encourage iPhone owners who did not upgrade last year to do so this generation.
"Retention has become very high for both Android and iOS - switching is largely a thing of the past," suggested analysts at UBS.
"Put simply, the replacement for iPhone is iPhone, the only question is when - and the when is driven in large part by form factor, namely the screen."
The latest phones feature a fresh processor - the A12 Bionic. It the firm's first to feature seven nanometre transistor technology, which should aid energy efficiency and computation speeds.
Its inclusion means the iPhone XS will last about 30 minutes longer on a battery charge than the X, Apple suggested.
The firm also said that its Face ID system would now work faster than before and it demoed several apps, showing off its augmented reality prowess.
Huawei recently announced it had developed a rival 7nm mobile chip of its own.
Despite rumours that at least one of the new iPhones would feature three rear cameras - like Huawei's P20 Pro - Apple stuck with two 12 megapixel lenses for the XS and XS Max. The XR only has one rear camera.
However, Apple did unveil a new feature that will allow users to alter the depth-of-field of their photos after they have been taken - effectively changing the degree to which the background is blurred.
"Apple will face some inevitable criticism that these products offer only small improvements on prior successes," said Ben Wood from the consultancy CCS Insight.
"However, the fact that Apple has sold almost two billion iOS devices to date is testament to the success of the iPhone recipe since 2007."
Earlier at its California event, Apple unveiled a new smartwatch whose display extends further towards its edges than earlier models.
he firm said the Watch Series 4's usable screen was more than 30% larger despite the device itself having similar dimensions to its predecessor.
It also gains the ability to detect if its wearer has fallen and to take electrocardiogram heartbeat readings.
Apple overtook Xiaomi and Fitbit to become the world's bestselling wearable tech company in the second half of 2017 thanks to strong demand for the last generation of its smartwatch. It has held on to the top spot ever since, according to IDC.
"The reason it performed so well is that many network operators are only willing to focus on smartwatches with their own [built-in cellular] connectivity," said Mr Jeronimo.
"That's why they are shipping about as many watches as the whole Swiss watch-making industry."