We have been discussed it on local board and thanks for Baofeng in mentioning this cite to search for a plagiarized content.
1. https://www.grammarly.com/plagiarism-checker
2. https://www.duplichecker.com/
3. https://www.copyscape.com/
That doesn't help in such cases.
But I suppose, considering the user is relatively new, the mods could delete his synonymized posts, ban him for a day or two, and give a one-off warning regarding such posting and giving them the benefit of the doubt. My take on this might be considered to be quite controversial, but I still want to believe the good in people so.
When someone does that as soon as they register on a forum I doubt the intentions are good.