They are very much likely to be banned than not (if and when they get reported). Although context can sometimes be derived, and posting history taken into account, I’d say that the vast majority of plagiarism is performed by lower ranks (or when accounts were lower ranks), when the accounts normally don’t have that much of a history to go by.

Probably quoting copied text is the better visual cue to use, since it makes it clearer that the intention is to bring to the post something not written by the poster. In any case, adding the reference link goes a long way if one is not capable of simply reading and expressing things with their own words.