Margot has just walked the red carpet at TIFF for the showing of her movie, I, Tonya. She is wearing a dress from the Erdem Pre Spring 2018 Collection!
For footwear, she wore the Silver version of the Jimmy Choo Metallic Leather Ankle Strap heels. I could not find the exacts online. Thank you @priyankachoprastyle!
For earrings, she possibly wore Tiffany & Co Inside-Out Hoop Diamond Earrings, available for £6,250. I am not certain of these as an exact match.