Yes, you can spawn basic meshes in 3,0 (for testing purpose I guess):
- Array
-Capsule
- Cube
- Cylinder
- Plane
- Prism
- Quad
- Sphere
But Godot is not a 3D modeler, for this purpose, look instead at Blender, which is perfectly compatible with Godot Game Engine via Better Collada (*.dae files) export.
What Godot manage:
- Animations
- Particle systems
- Game mechanics
etc.
So Godot don’t manage modeling yet, but in the future, who knows?
About Blender, there are tons of tutorials, videos and websites dealing with the subject all over the Internet.