If you know the children's mode of earlier Samsung smartphones, then you will not be able to find it on the Samsung Galaxy S8. This is no longer preinstalled from the factory.
However, if you want to reinstall it so that even children can use the Samsung Galaxy S8, then this simply works as follows:
Open the app menu and then the folder "Samsung". Here you will find the app "Galaxy Apps". This is the Samsung App Store, where you can now find the children's mode.
1. Touch the "Exclusive" tab at the top of the site
2. For Galaxy Essentials, select All apps
3. Scroll down the list until you see "Kid´s Mode" - Install this on the Samsung Galaxy S8.
You can then set up the child mode on your device. To do so, tap the app icon within the App menu. Finished!