I'm not familiar with the Duo. Stock Android should be able to display in split screen view and it looks like your LG is running at least Android 10 which should have this function. The way you enter split screen on most devices is to open each individually then open your multi-tasking/quick switch screen. Touch the app icon at the top of the app card on that screen and select split screen, then touch the other app. If both are compatible with split screen you should get one on the top and one on the bottom. If either is not compatible you may get a banner or it may not appear in the list. This would depend on the device.
If this doesn't answer you question please provide more details on exactly what you mean. As always more details usually results in more and faster answers, where single line questions are often difficult to always understand and difficult to answer as there are often several possible answers.