Cate Blanchett knew exactly what look she wanted for her character Catherine Ravenscroft in the limited Apple TV+ series “Disclaimer.” Despite playing a wealthy, award-winning journalist, she didn’t want to look like one, so she’d send costume designer Jany Temime pictures of boho society women as examples.

Temime wanted to make sure Catherine’s look wasn’t just feminine, but sexy, too. “If I had dressed her in trousers or big sweaters or shirts, you never would believe the story,” Temime says. Blanchett also suggested a touch of red in everything she wore — whether it was a scarf or a ring,...