The anime of My Dress-Up Darling typically ends at a certain point in the manga, but it's not always an exact match. Sometimes, adaptations make slight changes.
Sure, My Dress Up Darling has a manga. It provides the original story and character development that the anime is based on. The manga offers more depth and details that fans enjoy.
First, really understand the characters. Know their personalities, likes, and dislikes from the original work. Then, come up with an interesting plot. It could be a new cosplay project they take on or a relationship - building story. Also, use vivid descriptions, especially when it comes to the cosplay costumes and the process of making them.