In the world of One Piece, many characters possess varied heights and body types, making it challenging to recognize these characters solely by their silhouettes. However, the silhouettes in One Piece are often required to adhere to a very strict standard throughout the narrative.
Specifically, the silhouettes of One Piece characters often trend towards not resembling the final designs of the characters when they are officially revealed. In practice, this difference is quite significant and has led to the One Piece community continuously creating memes about this very issue.
Why the silhouettes of characters in One Piece do not resemble their final designs
In One Piece, typically when a character is officially introduced, other characters and background scenes will provide brief hints regarding their existence. For example, at the end of the Enies Lobby arc, Garp hinted at the existence of the Marine Admiral. Despite Shanks and Whitebeard being prominently featured, the only Admirals introduced at this point were Big Mom and, notably, Kaido, who was only represented through a silhouette.

Even when Kaido officially appeared, this silhouette did not resemble anything specific to the character’s final design in the actual series. Instead of portraying a colossal beast, Kaido’s silhouette presented a small, vaguely defined figure. Additionally, this phenomenon has occurred with many other secretive characters in One Piece, including the mysterious Loki.
Silhouettes in One Piece are primarily unfinished designs

One of the reasons that make these silhouettes look unlike the final designs is that Oda has not completely decided on the designs for these characters yet. Characters in One Piece have a distinct artistic style and vary greatly, meaning that the hints can be recognized immediately from a silhouette.
However, if a character’s design is still incomplete, it is better to use a simplified silhouette so as not to distract viewers from the finalized designs of One Piece. If not, if Oda commits to designing characters from the outset and provides an accurate silhouette, it will be challenging to revert and redesign characters that have already been completed.
Moreover, the hidden silhouettes of One Piece characters help maintain an element of mystery and anticipation for their eventual reveal in the story. If Kaido only resembled a basic silhouette in Garp’s narrative, it would make his later grand introduction lose its impact during the significant time skip. While the silhouette does not need to differ too much to convey this understanding, at the very least, it should be simplified enough not to create a comparison with the final design.