How large are those areas?
> details of who was in a geographic area, such as a radius of a few hundred feet at a certain point in time
It probably depends on whether the suspect was on foot or driving.
https://support.apple.com/en-us/HT207056#:~:text=If%20Locati....
TLDR Android & iOS Location Services will automatically contribute wifi data and correlate it with GPS. This can be audited to prove it's anonymously uploaded but it does happen.