I haven't seen any tutorials specifically for that. But you could do other tutorials to get familiar with Godot so you can learn to do it yourself.
Though the text edit boxes have focus properties (this will control what happens when you press Tab) I'd suggest doing it manually for a game so you have more control.
For example, you can create a Label and set the text property when a user types a letter. To get the letter you use the _input() method and you can read keycodes.
Then you can set an input map for your other buttons, like Space or Enter, that will go to another Label of your choice, depending on what happens in the game.
This is not a hard project, but you will likely have to do some research and learning with Godot cause I don't know if any tutorials will cover it exactly.