Samsung Galaxy S8/S8+ and Note 8 update adds home screen rotation option12
Galaxy S8/S8+ and Note 8. Up until now, Samsung Galaxy S9 was the only one with support for home screen rotation, but the update will add it to three other smartphones.
However, it looks like that the option to enable the landscape mode doesn't appear for everyone, even with the latest version of Samsung Experience Launcher, which suggests that Samsung is making it available to users in waves.
Or perhaps Samsung is just testing the feature, so only select users will receive it at first. In any case, you can go ahead and check whether or not the option is available on your phone by heading to Settings / Home screen settings. You should see a new “Portrait mode only” option that you can enable if you want your Home screen to rotate to Landscape mode.
source: XDA Developers