3D printing filaments with a ceramic superpower are a blend of polymer with ceramic powder. They print like a normal 3D printing filament however after printing the final product can be heat treated in a kiln where the polymer portion of the filament will de-bind from the ceramic. The ceramic can then be heated to around 1200°C in the kiln where it will sinter (shrink) by around 20%. After heat treatment the ceramic can be glazed and finished like a normal ceramic product.
Printing with ceramic 3D printing filaments requires some modifications to your 3D printer, such as an all-metal hot-end. The filament also needs to be pre-heated to around 50°C as they can be quite brittle when cold.
To maximise the potential of ceramic filaments a kiln is definitely required however even without one they are interesting filaments that can produce some great products.