An adverb used to emphasize that something is exactly or especially the case (used to stress or single out something).
この味はそれこそ家庭の味だ。
This flavor is exactly like home‑cooked food.
彼の言う通りだ。それこそ問題の核心だ。
He's right. That's precisely the heart of the problem.
忙しい時ほど、それこそ基本に立ち返るべきだ。
When you're busy, you should especially return to the basics.
Used to indicate strong certainty or clear truth (surely, unmistakably).
彼女の成功はそれこそ努力の賜物だ。
Her success is surely the fruit of her efforts.
それこそ彼が探していたものだ。
That's exactly what he was looking for.
この結果はそれこそ予想通りだった。
This result was unmistakably as expected.
Used figuratively to mean 'as if' or 'just like' (indicating a likeness or comparison).
彼はそれこそ王様のように振る舞った。
He behaved as if he were a king.
その光景はそれこそ夢のようだった。
The sight was just like a dream.
彼女の笑顔はそれこそ太陽のように明るかった。
Her smile was as bright as the sun.