in the book east of eden does the author use metaphoric or ironic decies

Okay, I'm pretty sure you mean "devices". I think there is a lot of metaphor in the novel. He specifically uses allusions to the Bible. Consider the story of Cain and Abel. The Trask family becomes a metaphor for the biblical story of Cain and Abel. Consider Charles and Adam. Like the Biblical story, Charles grows jealous of his brother Adam and attacks him in a fit of rage. Similarly Adam's sons, Cal and Aron, have their own feud. Charles's scar is also symbolic for the “mark of Cain” in the Old Testament story.