PrimitiveMesh provides convenient methods for creating mesh objects such as cubes and spheres.
The editor has built-in basic geometries such as Cube, Sphere, and Cylinder, which can be directly placed in the model by clicking + on the left node tree:

Of course, we can also click 1 in the component panel to add the Mesh Renderer component, and click 2 to bind the desired basic geometry:

Built-in geometries not meeting your needs? You can create a Mesh asset in the Asset Panel by right-clicking → Create → PrimitiveMesh, and adjust the parameters of the Mesh to meet your requirements.
The currently provided geometries are as follows:
const entity = rootEntity.createChild("cuboid");
entity.transform.setPosition(0, 1, 0);
const renderer = entity.addComponent(MeshRenderer);
renderer.mesh = PrimitiveMesh.createCuboid(engine);
// Create material
const material = new BlinnPhongMaterial(engine);
material.emissiveColor.set(1, 1, 1, 1);
renderer.setMaterial(material);const entity = rootEntity.createChild("sphere");
entity.transform.setPosition(0, 1, 0);
const renderer = entity.addComponent(MeshRenderer);
renderer.mesh = PrimitiveMesh.createSphere(engine);
// Create material
const material = new BlinnPhongMaterial(engine);
material.emissiveColor.set(1, 1, 1, 1);
renderer.setMaterial(material);const entity = rootEntity.createChild("plane");
entity.transform.setPosition(0, 1, 0);
const renderer = entity.addComponent(MeshRenderer);
renderer.mesh = PrimitiveMesh.createPlane(engine);
// Create material
const material = new BlinnPhongMaterial(engine);
material.emissiveColor.set(1, 1, 1, 1);
renderer.setMaterial(material);const entity = rootEntity.createChild("cylinder");
entity.transform.setPosition(0, 1, 0);
const renderer = entity.addComponent(MeshRenderer);
renderer.mesh = PrimitiveMesh.createCylinder(engine);
// Create material
const material = new BlinnPhongMaterial(engine);
material.emissiveColor.set(1, 1, 1, 1);
renderer.setMaterial(material);const entity = rootEntity.createChild("torus");
entity.transform.setPosition(0, 1, 0);
const renderer = entity.addComponent(MeshRenderer);
renderer.mesh = PrimitiveMesh.createTorus(engine);
// Create material
const material = new BlinnPhongMaterial(engine);
material.emissiveColor.set(1, 1, 1, 1);
renderer.setMaterial(material);const entity = rootEntity.createChild("cone");
entity.transform.setPosition(0, 1, 0);
const renderer = entity.addComponent(MeshRenderer);
renderer.mesh = PrimitiveMesh.createCone(engine);
// Create material
const material = new BlinnPhongMaterial(engine);
material.emissiveColor.set(1, 1, 1, 1);
renderer.setMaterial(material);const entity = rootEntity.createChild("capsule");
entity.transform.setPosition(0, 1, 0);
const renderer = entity.addComponent(MeshRenderer);
renderer.mesh = PrimitiveMesh.createCapsule(engine);
// Create material
const material = new BlinnPhongMaterial(engine);
material.emissiveColor.set(1, 1, 1, 1);
renderer.setMaterial(material);