One literary device Jane Austen uses in Sense and Sensibility is didacticism. The didactic novel was a popular form in the 1790s, which compared two ideologies and preached that one was right and one was wrong. In the case of Sense and Sensibility, Austen used didacticism to preach that the emotionally uncontrolled perspective taught by the Romantic movement is the wrong way to live your life, while governing your emotions through prudence and rational thought is the correct way.
Austen's classic use of irony can also be found in Sense and Sensibility. For instance, Dramatic Irony can be seen in Marianne's claim that love can only happen once. We see this claim of Marianne's made when Colonel Brandon asks Elinor if "her sister...does not believe in second attachments" (Ch. 11). Later during the story Marianne's perspective comes back to haunt her when, not only does Colonel Brandon fall in love with her after being brokenhearted, but Marianne falls in love with Colonel Brandon even after having her heart broken by Willoughby.