Model is wearing a size 12.
Available at Neiman Marcus
Size 4-6: https://www.neimanmarcus.com/p/zoe-girls-mila-ruffle-trim-chiffon-dress-size-4-6-prod251290294?childItemId=NMK1NF3_
Size 7-16: https://www.neimanmarcus.com/p/zoe-girls-mila-ruffle-trim-chiffon-dress-size-7-16-prod251290337?childItemId=NMK1NF2_