All iPhone 13s planned for 2021 would be entitled to LiDAR scanner, according to Digitimes. It only exists on the iPhone 12 Pro and iPhone 12 Pro Max to date. The iPhone 12 and iPhone 12 mini are not eligible for this.
The first Apple device with a LiDAR scanner was the iPad Pro last March. According to Apple, it allows for immersive augmented reality experiences. It is also used to measure the time it takes for light to be reflected from objects. It uses this data to create a depth map of the space.
The presence of the LiDAR scanner on all iPhone 13 seems quite logical in any case. Apple often offers features from its Pro devices to non-Pro models after a few years. This can be seen with the OLED screen which is now available on all iPhone 12. The iPhone 11 had an LCD screen for example.
The LiDAR scanner should not be the only novelty of the iPhone 13. The first rumors speak in particular of a screen with a display of 120 Hz on some models (certainly the iPhone 13 Pro). Better photo sensors would also be present, along with the A15 chip and a less power-hungry 5G chip. The new smartphones could well be presented in September, as was the case in past years. 2020 was an exception because of the Covid-19.