Foreign media 9to5Mac cited a number of sources familiar with the matter, due to important smartphone activities, mobile operators have been asking employees not to leave on 13 September.

That doesn’t necessarily mean the release is Apple-related, but the company is known for hosting iPhone events in September. While most iPhone launches are held on Tuesdays, last year’s event was held on 7 September, a Wednesday. Since 13 September is also a Wednesday, it’s reasonable to assume that Apple will choose that date for next month’s special event.
If Apple releases the new iPhone on 13 September, pre-orders are expected to begin on Friday 15 September, with the device going on sale a week later on 22 September. In contrast to last year, pre-orders for the iPhone 14 begin on 9 September and it officially goes on sale in shops on 16 September. Of course, there may be some exceptions.

Last year, due to supply issues, the iPhone 14 Plus went on sale on 7 October. 2020 saw a similar delay, which affected the release of the iPhone 12 Pro Max and iPhone 12 mini. Some analysts have predicted that at least one iPhone 15 could be delayed this year, while others believe that sales of all new models will begin in September, despite “severe shortages”.
According to previous reports, the iPhone 15 lineup will feature a slightly different design, with slightly curved screen edges and a thinner bezel around the display. All four new models will feature Nimble Island and USB-C, moving away from the Lightning connector. For the Pro models, Apple is expected to replace the stainless steel bezels with titanium ones.