There is no legitimate way for an unauthorized eavesdropper to access those specific packets. So let's break it down:
- Make it legitimate. Eve* could ask Alice or Bob for those packets.
- Authorize it. Eve could be a law enforcement officer, and request the network provider to deliver copies of those packets.
- Be less specific. If Eve is a thief who just wants to steal from anyone, there's no reason she has to hack a network in L.A.; she could hack one closer to home where she has physical access.
If Eve is prepared to engage in criminal activity, she would then have to hack into Alice and Bob's network, and gain access to one of the devices on one of the subnets carrying their traffic. Your specific example of 192.168.1.0/16 may be a problem for her, as that is a non-routable address range, commonly managed by home routers behind a NATting firewall (in other words, 192.168.. is not a unique address, it's shared by millions of home networks.) But she can find their network through some other means. One way is via an email embedded with an HTML image, which has to "phone home" to retrieve the image when the message is read. That will give her the routable ("outside") address of her firewall.
How she hacks into their network is as broad a question as "how to hack?" and can't really be answered. But let's say she gains access into the network by portscanning their firewall, and finding a hole opened by some irresponsible home automation device that uses UPnP. Let's say she gained access via an insecure thermostat's web interface.
If sniffing network packets is her ultimate goal, she'll need to access a machine capable of running packet capture software. This may require using a machine more capable than the thermostat she hacked into. So she may need to 'pivot' to another machine inside the victim's network to gain access to a PC. Once the thermostat is acting as a relay, she searches the network looking for other machines, and finds an unpatched PC. She takes it over, and from the victim PC, she establishes a 'reverse shell' back to her computer, giving her command access to it. On this remote PC, she'll install a packet capture program like tshark, and run it for a while. This will produce a capture file without the graphical interface. After capturing packets, she'll copy the packet trace file back to her computer and run a tool like Wireshark to view and analyze the contents.
* The set of placeholder names often used in cryptographic protocol analysis includes Alice and Bob, who want to communicate with each other; Eve, a passive attacker who can eavesdrop but cannot tamper with their communications; and Mallory, an active attacker who can both listen to and tamper with their communications. You may find it useful to understand and use these common names.