https://www.howtogeek.com/403606/bluetooth-5.1-whats-new-and-why-it-matters/

Bluetooth 5.1 brings new “direction-finding” features that will let Bluetooth devices pinpoint physical location to the centimeter, aiding in indoor positioning. This latest version includes features that will make for more reliable Bluetooth connections, too.

Current Bluetooth proximity systems can guess how far away a device—like your smarthome or smartwatch—is by using signal strength. They might know you’re a few meters away, but they don’t know the direction.  That’s enhanced with a new direction-finding feature in Bluetooth 5.1, which was just announced by the Bluetooth Special Interest Group (SIG,) the industry group that oversees Bluetooth. A positioning system can now determine the direction a Bluetooth signal is coming from. Combining distance and direction, Bluetooth devices can now figure out the precise location of a device down to the centimeter.