Oh no, not really.
First, you mean the Zuochan yi (Tso-ch'an i or Zazengi) by Choro Sosaku (in Japanese, aka Changlu Zongze or Changlu Tsung-tse in Chinese), which is included as one part of his "Zenen Shingi, Rules of purity for the Chan Monastery."
In those days, I think that the concept of "plagiarism" did not exist as it does now. So, when Dogen wanted to write a "how to" instruction on Zazen, he picked up one of the existing ones (the Zuichan yi) and basically rewrote it in most sections. He left some of the sections on the mechanics of sittings, like posture and crossing the legs, almost unchanged, but so radically reworked the rest so much, especially about the significance and attitude toward Zazen, that it is a radically different text and approach.
Dogen actually criticized the Zuochan yi in his own Shobogenzo-Zazen Shin. A book about the rewriting of the Zuochan yi by Dogen is this one, by Zen historian Prof. Bielefeldt:
https://terebess.hu/zen/dogen/BielefeldtDogen.pdf
Here is an example, 4 matching sections so you can see what Dogen did:
Tsung-tse:
Dogen:
So, you can see what Dogen did with the original.
Sorry to run long.
Gassho, J
STLah