USD Primitives
To create a new USD Primitive go to the Properties Panel of the Scene, and in the Outliner, click the Add Button, then hover USD Primitives:
Warning:
USD Primitives are not supported in all DCC, and in Pixar own word : "We in fact rarely render these primitives". They are here mostly to be able to override and move existing USD Primitives in your scene. You should rarely, if ever, create one yourself, as they have strong limitations compared to Mesh Primitives.