There are numerous reasons why your score may be a tiny bit lower than what the reviews have, your score will also fluctuate slightly as well. However the clock speeds of both the P cores and E cores look fine to me, 29k is also roughly in the ballpark of what you should expect.
I don't have a 13700K personally so I haven't had experience with this particular CPU or know a specific guide or values to recommend. However I have undervolted my 10850K, the process would be similar for both CPU's.
While there are multiple ways of doing it my personal preference is to leave everything as it is and apply a negative voltage offset. What this does is it allows the motherboard/CPU to determine the appropriate voltage and then reduces that figure with a fixed offset. So for example, if in Cinebench the motherboard determines a core voltage of 1.3v and I have a negative offset of -0.1v then the final voltage will be 1.2v.
The benefit of doing it like this is that the CPU clocks and voltage can vary as normal and all power saving features remain intact.
I posted on the below thread a while ago to assist someone with a 12700K, you may find it helpful:
Hi guys first time post here so bare with me. First illl start with Specs CPU - i7-12700k MBO - MAG Z690 Tomahawk Wifi DDR4 Cooler - Noctua NH-D15 (duel fan) GPU - 4070ti Case - Corsair 4000d Airflow Fan Config is 3 intake at front 2 exhaust top 1 exhaust back Now most of the specs are out of...
forums.tomshardware.com
There's also a video on their by JayZTwoCents on undervolting which is worth watching.
I would recommend starting with something small like -10mv (-0.01v) and then gradually increase it. I probably wouldn't go over -100mv (-0.1v) though I've seen posts where some people have. If you pursue this though you must make sure you are applying a negative offset and not a positive one, otherwise you will end up increasing the voltage which could damage the CPU.
As for your 209W, not all workloads are created equal, you can have two workloads that push the CPU to 100% but draw different levels of power. Prime 95 will push it well beyond 209W (I don't recommend running it). However I find Cinebench R23 a more accurate reflection of real world use.