All the patch notes mention is that the update contains the most up to date security patch for the device. So this is likely just about improving security for the Verizon models of the watch and nothing more. Verizon lists the release date for the patch as October 17. Which means this probably started going out to users yesterday. If you have a Verizon model of the Galaxy Watch 5, make sure to check your Galaxy Wearable app for software updates.

Only the Verizon model of the Galaxy Watch 5 seems to be getting the update

Right now no other versions of the Galaxy Watch 5 or Galaxy Watch 5 Pro appear to be getting the software update. This would seemingly include versions from other carriers as well as the WiFi/Bluetooth-only model. Verizon doesn’t state how big the update is. But given this is just a security update it shouldn’t be a large file to download. And once downloaded should only take a minute or two to install. The update can be downloaded either by WiFi or on Verizon’s mobile network. Verizon does recommend that you use a strong connection if you’re using its network though. So, probably not a good idea to try and download the update if your connection is spotty. You do also want to make sure that your battery is mostly charged. As the last thing you want is for the watch to power off in the middle of the update. With the Verizon update starting October 17, users may begin to see other versions get an update for security as well. So even if you don’t have a Verizon model, keep an eye out for updates as they may appear in the near future. Prior to today’s update, the Galaxy Watch 5 series got its second update back in the middle of September. This also the Verizon model only.