While Apple is updating iPhones as far back as iPhone 6s, the company might not be able to release some of the new iOS 15 features for the iPhone X and older devices.
Should you preorder the new iPhone 15 or stick with your iPhone 14? - Reviewed
Apple iPhone 15 and 15 Plus review: Dynamic Island, 48 megapixels, and new colors - The Verge
Which iPhone 15 is right for you?: Digital Photography Review
Face ID with a mask: Here are supported iPhone models - 9to5Mac
iPhone 15 review: a big step forward
iPhone 15 features: What the early rumors say
Apple Addresses iPhone 14 Battery Complaints With New iPhone 15 Features
Have an iPhone X or older? Here are ten iOS 15 features that you won't be getting - SoyaCincau
Close an app on your iPhone or iPod touch - Apple Support
iOS 16 - Features That Won't Work On Older iPhones