Definitely not. Godot 4.0 attempts to convert the project, but lots of manual work is still needed. There have been significant GDScript code changes, so you'll have to change some of the scripts. Some are simple, like Spatial being renamed to Node3D (which can be automated search and replace). But others, the API has changed and require more work. In addition, materials are different and usually need to be redone. On some of my small demos it took around 3 days to port to Godot 4.0. For a full game, it would probably take several weeks. And I wouldn't recommend porting now, as the API is still changing. I wanted to get a head start, so I switched to the 4.0 alpha already, but there are lots of bugs. It's still usable and works okay, but it's rough. My estimate is that the beta will be out later this year and the stable official release will be in early or mid 2023.
