Is it plagiarism to copy formulations from others?
Sentence patterns are not intellectual property; otherwise, every author who wrote "To X or not to X" would be plagiarizing Shakespeare. (They are "riffing" off of him, but not plagiarizing!)

The example you are citing is perfectly innocuous, particularly since you are not doing anything more than summarizing the paper contents. The only thing that would make it wrong would be to copy those sentences directly from someone else's work.