Quiet luxury describes a style that conveys quality through materials, workmanship and restrained details, with little emphasis on conspicuous branding.
An understated piece can still be recognisable. A client might notice the handle of the cloth, the precision of the cut or a small finishing detail before identifying the maker. The phrase is a way of describing those visual choices. A neutral colour or a high price tells the customer little on its own about how a garment was made. Someone explaining the style can point to the particular material or detail that creates the impression.
In job listings
This is more a phrase from fashion commentary than from job descriptions. A candidate is more likely to meet it in a conversation about a house’s image, where naming materials and workmanship will say more than using the phrase. Search local jobs for “fashion”.