On the Samsung Galaxy S6 the Samsung keyboard is usually set as the default. The Samsung keyboard occupies about one-third of the display when an app is opened, in which you can write text. Now it is probably the case, that the keyboard is a bit too small for you and you want to adjust the keyboard size.
Super, you have luck! Because on the Samsung Galaxy S6 there is now the opportunity to adjust that (did not work in earlier versions). To adjust the keyboard size on your Samsung Galaxy S6 please proceed as follows:
1. Open from the Home Screen the menu and then the Settings
2. Select here "Language and input" and then proceed to "Samsung keyboard". Tap on the entry.
3. Scrolls the next submenu down to the section "Customization" and then select "Adjust Keyboard Size".
4. Above the keyboard you see now two arrows pointing up and down. You can now adjust the keyboard by moving these arrows up and down.
You've just adjusted your keyboard on the Samsung Galaxy S6. This is now displayed in the selected size in any application where text is written.