Is allusion a rhetorical device?

Yes Allusions are a rhetorical device, and "allusions" are allusions, including historical myths and legends, historical stories, poems of predecessors, historical figures and so on. Citing stories or words in ancient books as allusions can enrich and implicitly express related contents and ideas. The function of allusions is to strengthen the argument, enhance the persuasiveness of the argument, express their unique views by quoting allusions about historical figures or stories, trigger associations and innovate artistic conception.