True, for non-native authors writing in English, manuscript writing involves some amount of "imitation" as you have suggested, but that is more about imitating the style, not the content: for instance, you need to read other published works, summarize what they state in the literature review, sometimes borrow ideas or methodologies, and follow the style used in academic writing. However, if you use material from another study, there are chances that your work might be considered plagiarized.
Paraphrasing is a technique that allows you to borrow ideas from other works so as to avoid plagiarism. Of course, even if you paraphrase something, you should cite the source. If you do not cite the source properly, your paraphrase might also be considered plagiarized.
Here are a few tips on effective paraphrasing:
- Read the original text several times till you understand the meaning very clearly.
- Without looking at the source, jot down in points whatever you have understood from the text.
- Rewrite the material using your own words, but without changing the meaning.
- Compare with the original to ensure that you have used as few words from it as possible.
- Use quotation marks wherever you have taken a term or phrase verbatim from the original.
- Cite the source.
For a more detailed explanation, watch this video on how to paraphrase English text effectively.