Let's do some power scaling.
-The First Flame sustains all of reality, including all the metaphysical concepts like the flow of time itself.
-To link the First Flame requires a soul powerful enough to fuel it.
-This means anyone powerful enough to link the fire has a soul so strong it can literally power the whole universe.
-The Soul of Cinder is a being made from the amalgamated souls of everybody who has ever linked the fire.
-The cycle has repeated so many times countless entire civilizations have risen, fallen and been lost to history and all living memory between every single game. Meaning the fire has been linked an incalculable amount of times.
-This means the Soul of Cinder is made of an infinitude of souls, each with the power of a whole universe inside it.
-The Ashen One fights and defeats the Soul of Cinder.
Conclusion: the protagonist of Dark Souls 3 could beat up Goku.
