You can keep track of the IP address that you hear first announce a transaction. If you have enough nodes logging this across the bitcoin network, and someone c

You can keep track of the IP address that you hear first announce a transaction. If you have enough nodes logging this across the bitcoin network, and someone connects a node running on their personal compute to the network in order to initiate a transaction, then you can basically have the location data for the person who initiated that transaction. (There's a whole bunch of caveats here, but that is how it would work at a high level)