Zoro's Asura:
1. Strongest technique of 3-sword style. I can't remember what his strongest attack with 2-sword style, but Shishi Sonson is his strongest technique for 1-sword style.
2. Unlocked the Shishi Sonson due to his mastery of nature of cutting blade, while unlocked Asura due to mastery of his willpower/spirit.
3. Zoro's strong willpower hinted way earlier in the series, since his beaten up by Arlong.
4. Enma enabling him to further unlock his COC.
5. His mastery of Enma background another further unlock of Adv COC (I hate to admit this tho)
Sanji's Diable Jambe (DJ):
1. By comparing against Zoro, it's pretty much like Zoro's Shishi Sonson. The first time introduced, it's more like Charlotte Oven's Heat DF. Where Jyabura describe it is RED and Glowing. Clearly shown that Sanji use friction technique to create DJ initially. No doubt bout that.
2. In other word, by power unlocking, Sanji at Enies Lobbies arc achievement can be considered same as Zoro's achievement during Alabasta arc.
3. Post time skip, Sanji show his growth by enable to create fire via 'passion' only. No more 'friction'. His whole body covered by flame tho.
4. Come to Wano arc, thanks to Enma, Zoro 'attain' COC, while Sanji 'attain' Germa genetic unlocked. This advantage splendidly used by Sanji to allowed him increase his flame-level which resulting Ifrit Jambe (IJ).
5. Quite clear note that Sanji can actually use IJ before reunion his Germa family and wear Raid Suit (RS), but he only choose to use it now due to currently his leg can wield much hotter flame compared to before genetically modified thru RS.
6. Thus, Sanji unlocking of Germa genetic, further increase his attacking power to match up with Zoro's Asura.
7. While Zoro enhance his 3-sword style with Adv COC, pretty sure Sanji imbued Adv COA to do IJ.
8. To further comparison, Zoro's 3-sword style with Adv COC and Sanji's IJ with Adv COA is on the in the level of Luffy's Gear 4th.
As conclusion, provided anyone obtained Zoro's Enma or Sanji's Germa genetic, they can achieve this power level. The key is the concept as DF Awaken level by mastery the fruit power mentally and physically.
p/s;
To Zorotards, I'm not trying to put Zoro weaker than Luffy or Sanji as strong as Zoro. It's another case.
To Sanjitards, I bet Sanji still have further unlock to look for in future.