General

It depends on the occasion of course. And on body type

Overall nothing that hides the body.
Confidence is the sexiest thing a BBW can wear.
It needs to fit her overall style and vibe.

That said:
Beach or pool —> bikini for the top I don’t really care as much. But for the bottom, nothing that cover to much. So Brazilian cut not over the belly.

Relaxed outfit:
Bike shorts or leggings with a crop top

Other than that:
I really like pleated skirts that accentuate hips and hourglass figure
Heels or plateau (for the heavier ones)
Or thigh long dresses

As a growing BBW

Maternity pants for more stretch and room for my belly..maternity shirt so it help show my belly more...also stretch pants/ leggings and a crop top or regular shirt

As a growing BBW that likes to be teased I love to show off that I'm getting fatter.
For me the most attractive clothes are to tight skinny jeans, showing off curves, but not to much.
The waistband digging deep into my belly, letting a huge roll of fat hanging over it. A tight shirt that barely covers my gut, but reveals a bit of my stretchmarked belly when i move 🥵

Tight low riding jeans so that belly can hang over the waistpant and too short crop top that doesn't cover the belly

When I'm out at a club or a nice restaurant I love seeing a BBW in a tight, form-fitting gown that accentuates the curve of her hips, and shows off the nice round bulge of her belly.

Edit: After some additional research, I think the term I was looking for was "bodycon dress." Sorry, I'm a guy; I don't know much about women's clothing