AE // unpremult (kind of)

Use the effect remove color matting (create an alpha before with shift channel or other if no alpha exist)

AE // fill alpha with solid color

Use the "solid composite" effect

AE // unpremult

use the channel combiner effect with solid alpha checker to unpremult (kind of)

AE // light wrap

or just a layer style


and set 0 to fill opacity to just have the effect