For sibling chips like this, yes. Two cores being run at 90% utilization each will draw about the same amount of power regardless of whether you bought the 6-core version or the 8-core version.
Similarly, 4 cores running on the 12 or 16 core chips should eat about the same amount of power as each other.
Similarly, 4 cores running on the 12 or 16 core chips should eat about the same amount of power as each other.