Well, smut manhwa typically features themes and scenes of a sexual nature. It's not for everyone and is usually targeted at a mature audience. These comics can vary in their level of explicitness and storylines related to sexuality.
A yandere girl in manhwa is often extremely possessive and obsessive about the person she likes. She can go to extreme lengths to keep them close, sometimes even resorting to violence or manipulation.
In manhwa, yandere boys typically have a dual personality. They might seem normal on the surface but go to great lengths to keep the object of their affection close. Their actions can range from overly protective to outright violent when they feel threatened.
Common traits of harem manhwa smut include a male protagonist surrounded by several interested females and a lot of sensual and adult-oriented content. The plots can sometimes be light on story but heavy on the romance and intimate moments.
You can try some online comic platforms that specialize in adult content. But be aware that accessing such content may not be legal or ethical in some cases.