Yes it technically has the capability to do almost anything, but any 3D stuff that you do will be almost entirely your own code or another graphics library. You can definitely do 3D stuff, it just won't use the greenfoot API. (Also it's obviously more challenging)
CrazyGamer, it is also really useful to understand the code of Builderboy, instead of just using it. Search the web for z buffering if you wanna find out more.
That would take very long, especially for a beginner like you. I'm currently werstling with it, and I find it quite hard. You'll see it is way harder than you think right now!
I think if you really want to you'll at least be able to make a start, then come back to it later. If you're motivated you should be able to get at least something working :D!
CrazyGamer1122, If you want to write it by yourself, I would recommend starting with something simpler, like a cube runner game, that does not incorporate rotating the camera. The code behind that is much simpler. Then the next step would be a first person shooter.
@MatheMagician Well, if you use raycasting (like your cube runner game) you do can rotate the camera, but you can't look up or down. And that's not just about the less code: it is because of the technology behind it (raycasting doesn't support looking up or down)
CrazyGamer1122, If you want to write it by yourself, I would recommend starting with something simpler, like a cube runner game, that does not incorporate rotating the camera. The code behind that is much simpler. Then the next step would be a first person shooter.