iPhone 12 Pro models feature a new LiDAR Scanner for enhanced augmented reality experiences, but the sensor also enables another unique feature: the ability to measure a person's height instantly using the Measure app. You can even measure the seated height of a person in a chair, according to Apple.
When the Measure app detects a person in the viewfinder, it automatically measures their height from the ground to the top of their head, hat, or hair.
To measure a person's height, open the Measure app and position the iPhone so that the person you want to measure appears on the screen from head to toe. After a brief moment, a line will appear at the top of the person's head with their height measurement, which appears in either feet and inches or in centimeters depending on whether imperial or metric is selected under Settings > Measure > Measure Units.
The circular shutter button in the bottom-right corner allows you to take a photo of the person with their height measurement and share it with them.
This feature is limited to devices with a LiDAR Scanner, including 2020 iPad Pro models and the upcoming iPhone 12 Pro Max.
Source: Macrumors