While creating Daenerys Targaryen's wardrobe, Clapton put an emphasis on the negative space above the Breaker of Chains' head, because she isn't allowed a crown.
Like Sansa, the Mother of Dragons sports a dramatic chain, but unlike Cersei, Dany lacks the crown. In an interview with Insider, Clapton simply stated, "You can't have a crown until you are queen. You can have the chain, but until you get the throne you're not queen."
Dany's costumes have evolved throughout the show from the early days when she adopted the leather-clad warrior style of the Dothraki and by the end, she was wearing more military robes as the figurehead of her army and the chain she wears was very much chosen as a means to express her ambitions.