How do I find another persons locating that have a iPhone
How do I find a location on another iPhone
iPhone 11 Pro
Question marked as
See: Find friends and share your location with Find My - Apple Support
Or if you mean that you want to find a lost phone by using another phone, use any internet browser and log into www.icloud.com/find
Also see: If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support