How to Find the Thermal Resistance Junction to Ambient
You will find detailed data on the LFPAK33 package in this document LFPAK MOSFET thermal design guide.
As a rule of thumb, in an automotive environment with 80°C max Ta, the maximum power dissipation on FR4 laminate is 1W. At 85°C it will obviously be less.
So you can forget about your 14W without a very, very substantial heat sink or equivalent structure to remove the heat.
The 79W is not only with a heatsink, it's with an extremely unrealistic heatsink that holds the mounting base temperature at 25°C despite 79W flowing into it. You might be able to accomplish that by fast-flowing chilled water through a copper heatsink. In short, it's not a realistically useful number except as kind of a theoretical extrapolation.
As an aside, I fear we are losing the intuition of power dissipation with the phasing out of incandescent bulbs. Anyone who has unscrewed a 60W or 100W incandescent bulb just after it has been illuminated for some time will know what I mean.