Sukunahikona

We know when Kawaki’s dojutsu increased to 4 lines he was able to use the Cubes, and pillars that even jigen wasn’t able to. And we know Jigen couldn’t fully shrink the flames Koji used but Isshiki who had 8 lines in his eye was easily able to. Meaning the evolved Dojutsu does increase the control, power and possibly the speed.

I think Kawaki/Isshiki both have the Full Power of the Daikokuten/Sukunahikona and the speed does increase. As well as the control. But as the manga progresses we will get answers

(Trick question) explaination below

contrary to what the fanbase believes Isshiki was already at FULL POWER. That’s exactly what the problem was! When Isshiki reawakened in jigen he was brimming with SO MUCH POWER his body couldn’t contain it and would crumble from that power in 2 or 3 days. To put it simply He didn’t need kawaki to make him full power, he needed kawaki to contain the full power.

While this is atypical, I think that there is a popular misconception that Isshiki's unnamed dojutsu is what performs Sukunahikona's ability. Instead of merely performing the technique, I think that the eye itself is the Sukunahikona dojutsu itself as its visual. While it lacks the -gan syntax associated with other dojutsu, the eye and dojutsu are not mutual exclusive. ~~~~