Not all of them. While a significant portion of the Gintama manga has been adapted into anime, there might still be some storylines or arcs that haven't made it to the screen yet.
Well, 'op' usually means 'overpowered' in fanfic terms. So 'percy is op fanfic' might be a fan - created story where the character Percy is depicted as being extremely powerful. Maybe he has extraordinary abilities, like super strength, or the ability to control elements in a way that makes him stand out compared to other characters in the story's universe.
I recommend the book "Possibly a Fake Silver Soul". It tells the story of Jiang Cheng, a transmigrator, who met the owner of Xinghai District and his girlfriend, Jiang Hua, who were traveling in the universe in the dragon vein of a certain planet. Later, he came to Earth and met his teacher, Yoshida Shoyo, who had influenced his life. He also met a group of friends. This included the transmigrator Okita Soki. This is a Silver Soul Doujinshi novel, don't miss it. I hope you like this fairy's recommendation. Muah ~😗
Gintama is purely fictional. It's filled with imaginative characters and scenarios that are not rooted in real-life events. The creators crafted a unique and entertaining fictional world for the audience.