Margot’s top is the Rosie Assoulin Bow-Accented Silk Bustier in the colour Yellow, not yet available. If you recognise it, it’s because it’s very similar to the same Black one she wore in 2016 when promoting Suicide Squad!
Her pants, also Rosie Assoulin, are the Sash-Tie Silk Wide Leg Pants in the colour Yellow. These are also unavailable to buy. I believe Margot’s is not including the sash.
For footwear, Margot wore a pair of Toteme Flip-Flop Heels in the colour ‘Nature’. The kitten heel sandal is available for €360.