I need to view when a device was last automatically connected to my phones bluetooth, because the device has been stolen and it would give me a time stamp of when it happened.
What device do you have? Different devices have different ways to get to things. It may also affect the information stored/provided/available as well.
On my Samsung it's, Settings>Connections>Bluetooth>3 dots upper corner Advanced>Bluetooth control history. And that only tells me the name of devices that have turned on or off my Bluetooth, not ever device that has been connected or when they were connected.
Samsung also has Smart Things. It has a history but when I check mine it shows nothing even though all of my BT devices are listed in the app...? It shows me the last time it saw my Smart Tags and where but no real history.