Best thing is to post the file and give the component number or specification of the component and the PCB specification (thickness of copper and fr4 for each layer).
Normally you would use the 'two-resister' method to represent an IC. With this method you can get both the case temperature and junction temperature.
If you are comparing CFD to a bench test attention must be taken to fully represent the setup on the bench. In a room the air is allays moving from people, hvac system, solar heating from windows, the bench blocking air flow, the wall blocking air flow, temperature stratification other equipment - where in CFD at the domain limits the air will have an absolute 0.000 velocity and constant temperature (at the start). Typically the EE will give you the worst case calculated power. It is best to get the measured power from the bench test, log the exact ambient temperature, capture the physical reality.... For natural convection your domain needs to be large.