People like Gabrielle Chanel, Hubert de Givenchy, Pauline Trigere' and Hardie Amies all designed for film, but made clothes that were entirely couture in aspect. To be fair, in each of those cases, the designers were selected for exactly that reason, either because the characters they were to dress were the sort who would wear couture, or because. as in the film Funny Face, it took place within the couture realm.
Only a few designers have been allowed the freedom to create true flights of fancy that stepped out of the couture and into another place. I'm thinking primarily of Hardie Amies who designed the costumes for 2001: A Space Odyssey, (and is the only one to have worked in both ways in film), Paco Rabanne, who got to design the wildly fun costumes for Barbarella, and Jean Paul Gaultier, who did the costumes for The Fifth Element. In two of these cases we are dealing with Science Fiction fantasies, having more to do with imagination than hard speculative fiction. And in both cases the results were delightful, sexy and fun. In the case of 2001, Amies was tasked with trying to realistically envision the world as it would be 40 years hence.
2001: a Space Odyssey was a groundbreaking film for Sci Fi costume. Never before had there been a serious attempt to create fully logical extensions of ongoing trends in fashion so that the result made real world sense. Prior to this film, the reliance on metallics, plastics and exaggerations of shape and proportion, made the results obviously costume, not real clothing. You could certainly argue that Hardie Amies typically conservative design style resulted in clothes for the film that stepped not very far away from the world of 1968, and you'd be right. What makes them work is that they are devoid of all sorts of silly gimmicks. They look like real clothes worn by real people for real tasks. Even the space suits look entirely functional.
We wait almost 30 years before we get to see another melding of couture designer and major fantasy. The Fifth element, from 1997 was designed by Jean Paul Gaultier, and gave him plenty of room to express his humor, his commitment to blurring gender lines and his resistance to anything remotely staid. The work he did is frankly sexy, sometimes deliberately amusing, and always dramatic and cheeky.
Look around, you'll see what I mean.