If they were located in a solar system, they would be considered large terrestrial worlds. As it is, Kauketean worlds are found well outside of solar systems. They are between about 2 and 5 Earth masses, with a hot core which is still cooling down. The gravity is enough to have retained a dense atmosphere, which is itself scorching hot. Surprisingly for a world so far from any star, they are considered to be hell worlds.
Their atmospheres can vary, from carbon dioxide, to hydrogen or helium. Often they are a mix, with the original helium or hydrogen atmosphere being added to by carbon dioxide as it is heated out of the planet's rocks.
If there is surface water, it is under high pressure, sometimes with a boiling transition layer between the liquid beneath and water vapour above.