The First Person Starter has officially been ported to #godotengine version 4.
You can get it from here: https://github.com/Whimfoome/godot-FirstPersonStarter
If you find it useful and want a whole bundle with starter projects including:
- First Person
- Third Person
- 2D Platformer
Visit: https://whimfoome.itch.io/godot-starters
They will be updated to Godot 4 in the following days.