How to turn on the system keyboard?

I'm trying to type something into a text field (for debugging, for example)

The Android/iOS soft keyboard does not lift. Upon contact with the screen, some kind of cross appears.

Is there a way to turn on the keyboard through some kind of setting or flag, as it is done in 

https://github.com/appium/appium-flutter-driver  via enableFlutterDriverExtension(enableTextEntryEmulation:false)