Big dick energy is so last season. To be alpha this autumn, you need big coat energy. Before you buy a coat this season, you need to ask yourself not only whether it will keep you warm, but also whether it will project the kind of quietly bulletproof confidence to which other people are magnetically attracted. Just like its NSFW namesake, BCE is not about swaggering or showing off. BCE is what happens when you get dressed and instantly feel more powerful, like Harry Potter after he pulls on his invisibility cloak.

Great in grey ... Julianne Moore at the Tory Burch show. Photograph: Cindy Ord/Getty Images

This is not a size thing. Just like BDE, BCE is not literal. At New York fashion week, Nicki Minaj had BCE sitting front row at Opening Ceremony in an enormous banana-yellow padded jacket, but so did Julianne Moore, wearing a menswear-cut charcoal blazer at the Tory Burch show. BCE does not have to be about a coat that requires a second seat on the bus or an oversized price tag. It is about the confidence that comes with knowing that you have nailed the most important fashion decision of the year: your new-season coat.

Even though size is not everything, it is a good place to start when harnessing BCE. The general vibe of fashion over the past half-decade or so – I am oversimplifying wildly, because we don’t have long – has been towards looser clothes, longer hemlines, a more covered-up aesthetic. It has already happened in your knitwear drawer: where you used to have fitted V-neck sweaters and cardigans so dinky in sizethat the buttons were wont to gape, now you have sweatshirts and polo necks. It has happened to your summer dresses: if you bought a holiday dress this year, it was likely below the knee, which would have seemed eccentric a few years ago. Now it is happening to your coat choices. Instead of a top layer that fits snugly over your clothes, many of the most desirable coats of this season are deliberately roomy.

Catwalk coats ... Balenciaga, Oscar de la Renta and Givenchy. Composite: Guardian Design Team

When I say roomy, I do not mean too-big. This is not the photogenically shambolic Justin Bieber/Kanye West vibe. A coat is a major purchase: it can be fun, but it should never be a joke. When I say roomy, I mean Marlene Dietrich in a generously sized trench in A Foreign Affair. I mean Kim Kardashian-West in a lavish Max Mara teddy-bear coat. I mean the lipstick-red wool beauty that opened the Oscar de la Renta autumn/winter 2018 show, cosy as a double duvet and closed at the navel with an outsized diamante brooch.

A coat having BCE can be as simple as it being double-breasted, rather than single-breasted. There is something naturally swashbuckling about a double-breasted coat left undone; it is very BCE. At Reserved, the blended wool coat (£74.99) comes in a modish lilac and has a pleasingly swingy silhouette when left unbuttoned.

If you fear being swamped in a double-breasted coat, a car coat style that falls to your upper thigh – somewhere in between a blazer and a “proper coat”, in terms of weather – is easier to wear and will work most of the year, give or take a freezing fortnight or two. The double-breasted jacket (£199) from the revamped fashion offering at John Lewis & Partners is made from double-faced wool and comes in camel or orange – very BCE, if you can pull it off.

High-street offerings ... Reserved’s blended wool coat (£74.99), Topshop’s wrap padded jacket (£55) and & Other Stories’ leopard-print jacket (£89). Photograph: Guardian Design Team

Catwalk fashion is always a cartoonish version of real life and the autumn collections were big on exaggerated proportions. Traditional checked-wool coats came with quarterback shoulders at Givenchy and padded hips at Balenciaga. Nubbly teddy-bear coats fell all the way to the floor at Giambattista Valli. What this means for your coat choice for the season is not a Jessica Rabbit hip curve or a hemline that will drag in puddles, but it may be a round shoulder shape that makes your silhouette softer and curvier or a hem that dips well below your knee. (The manxi – a cross between the just-below-the-knee midi and the ankle-length maxi – is the hemline term to drop this season.) If you buy a trench, you might make it a softly voluminous version, such as the oversized trench coat by & Other Stories (£155). The wrist ties on the sleeves are very BCE.

A leopard-print coat has always had BCE. When the Erdem x H&M collaboration launched in November last year, the leopard-print faux-fur coat with a black ribbon tie was one of the first pieces to disappear off the rails. This autumn, catwalk inspiration from Dolce & Gabbana and Victoria Beckham, whose leopard trench was the most-posted look from New York fashion week, has fed into high-street versions everywhere. A full-length leopard coat is a big commitment, though; I feel like there is plenty of BCE in & Other Stories’ leopard-print jacket (£89), which looks great with jeans and a white T-shirt.

A grand but elegant padded jacket is, like last year, the weird-on-paper-but-actually-deeply-covetable coat choice. There were chic, caramel-toned padded coats on the Roksanda catwalk and there are quilted coats in every colour of the rainbow all over the high street, in homage to Burberry’s multicoloured padded coats: the wrap padded jacket at Topshop (£55) is zingy in apple green. Winter may still feel like an abstract concept, but it is coming and it will be cold and long and tiring. A little BCE will get you through.