I wouldn't really expect significantly better efficiency. Especially as Intel is struggling with vulnerabilities. Whatever improvements they make can get eaten by mitigations. If you extrapolate for the 9900KS, ten cores running at 5 GHz would make it about 213 W. For a top bin vs. 4.6 GHz @ 224 W for the lowest bin. And truth be told, I don't really care that much in a desktop with beefy cooling.
However, the 9900 has 65 W TDP. Going from 65 to 170 seems strange. I don't know what to make of that number.
It would be interesting to compare it with a 9900. That also has 4.6 GHz all core boost IIRC. And can break 230 W with the right workload (hello, AVX :-) ). As loads matter. With one "stress" test, it can be 130 W. With another, it's 230 W (same frequency). It also depends on the motherboard and setup. Some motherboards wouldn't allow you to pump 230+ W into a 9900, so it wouldn't be able to keep the boost pinned (I think it would drop under 3 GHz on a standard setup). And it can be the same story with the 10900F. I really am not expecting to see 170 W TDP on that thing. What would have to be the base clock, anyway, for it to be that high? And with stock settings and running within Intel specification, I don't think it's going to take 220+ W. Yes, on the right motherboard with the appropriate setup, you might break 250 W (extrapolation would suggest that you might approach 300, if the God of silicon allows).