Cloten, dressed in Posthumus's clothes, is in Wales, near the place where Imogen is supposed to meet Posthumus. He says the clothes fit him well, and thus why should Imogen not prove "fit" (sexually available) for him, too (line 5)? He feels that he compares well to Posthumus in youth, looks and strength, and surpasses him in birth and advantages. He predicts that soon he shall have raped Imogen, cut Posthumus's clothes to pieces in front of him, and cut off Posthumus's head. The he plans to send Imogen home to face her father. Cymbeline may be angry with Cloten for treating Imogen roughly, but the Queen will take Cloten's part and make him appear worthy of praise.
Cloten's superficial awareness is again highlighted in his naeve faith that wearing Posthumus's clothes will play some part in allowing him to steal his wife. Bound up on the level of outward appearance, Cloten has no concept of true worth.
Cymbeline: Novel Summary: Act 4 Scene 1