Former Dior designer Raf Simons quietly arrived in New York after being named Calvin Klein’s chief creative officer in August — but there’s already speculation about how he’ll shake up the sleek brand as he’s begun working on initial plans at its Manhattan headquarters.

Sources tell Page Six that hot LA artist Sterling Ruby — Simons’ best friend and past collaborator — has been seen regularly at Calvin Klein headquarters, which has fashionistas wondering how he could figure into the brand’s plans.

One source said Ruby may help come up with a new concept for the Calvin Klein store on Madison Avenue, which has been called a “vast gallery-like space.” “That would be a huge departure from the sleek look they have now,” the fashion insider said, since Ruby was a former pro skateboarder influenced by California punk rock.

But another source insisted there are no current plans for a Ruby store redesign, and “there are just people out there speculating . . . Sterling has been in and out of the building. He and Raf are best friends. Of course they are meeting.” We further hear Ruby is in town because he has his own big art show coming up in March.

A 2014 profile of the duo called Belgian designer Simons and Ruby “a true, collaborative brotherhood,” and they sent a collection down the runways of Paris fashion week the same year.

Meanwhile, Simons — who’s been called “one of the great talents of his generation” — has been keeping such a low profile in New York since his arrival, some insiders didn’t even realize he’d officially begun work in the city. Stars wearing his line have not been as shy: Rihanna was spotted recently in an “oversize and destroyed” V-neck from Simons’ new collection.

But “they are keeping things private,” said a source of Simons’ CK team, adding he’s in meetings all day long. Part of the plan will certainly be to expand Calvin Klein’s high-end fashion business, which reportedly represents less than $10 million a year out of $2.9 billion in revenue. “He wants to pour more resources into the runway and ready-to-wear business,” a source said.