I made a Webench-Simulation, the ICThetaJA Effective is given with 6°C/W (Effective IC Junction-to-Ambient Thermal Resistance).
In the datasheet the value RθJA Junction-to-ambient thermal resistance is given with 42.9°C/W. I dont think that this value can be reduced such
like this, also with a perfect layout design (I dont know what kind of layout Webench use for this desing). I hope according JESD 51-7.