It's been a while when I last checked my settings due to a new job, but some notes from my memory.
Voltages depend on each CPU but I have 7800X, 9900X, 7980XE and W-3175X and each of them share roughly same characteristics when overclocking. My 7800X is the best which can do even Prime95 5.0 GHz, 9900X is the worst not stable past 4.6.
Core: Baseline for all of them is 4.5 GHz and it would take between 1.15~1.22V to reach those clocks for core. You just have to test. I use Prime95 with AVX disabled but you can use whatever you wish for stability testing. W-3175X seems to take around 1.2 V for 4.5 so it's not a very good CPU. To run CB at 4.6 I need already 1.24V.
Cache: For my CPUs 3000 MHz on the cache seems to be between 1.075~1.12V. On 7980XE/R6E combo to get 1.112V for cache it is +175mV on offset voltage and for W-3175X/Dominus this for some reason is +200mV. Measured with multimeter from the boards directly. Cache seems to be the one causing most of any weird behavior together with memory settings, often it is not even the core voltage acting up.
Input voltage: Use between 1.7-1.9V, and adjust the LLC to keep it stable. I think you should need to stay at least at 1.65V under load, preferably closer to 1.8V for heavy load. LLC doesn't affect core voltage, only input voltage. I've read some try to shoot this one as low as they can to gain some thermal headroom, but if you go too low you can see worse scores eg. in Cinebench or instability.
VCCSA: I actually run VCCSA stock on both platforms and I think it is staying at around 0.9 V. Better to check what your board is giving with XMP.
FOR CB20 I only found an old screenshot for now when I experimented some OCing on a cold day...but if you wish you can check my build log with some screens and pictures from the build on our local forum, if linking is allowed. It is in Finnish though.