No, due to the pressure within the mantle and even between the crust and the mantle. The asthenosphere, for example, is generally solid due to that pressure; it’s actually when the pressure goes down that molten magma can form, as I understand it.
Also, the planet’s outer core is liquid iron and nickel, but the inner core is solid; but the temperatures down there are as hot as the sun’s surface.
That's the theory, anyway. Until we have the technology to make real world observations of the interior cores of planets, we can only hypothesize about their structure.