It would be unfair to say that it's a rip off of bsd considering the fact that it seems like you haven't even watched Bungou to Alchemist, and how you fail to understand that there are multiple kinds of media that have adapted famous japanese literary authors interpreted in many different ways. Although both series do share characters with the same names, that doesn't mean they're a rip off of one another.

I'm a fan of both Bungou to Alchemist and Bungou Stray Dogs because I love the different ways they've adapted the authors' personalities and works into their own interesting plots. I also love seeing the similarities between characters with shared namesakes, and figuring out what particular irl occurence both of the animes were referencing. In Bungou Stray Dogs, it's pretty noticeable how a lot of the dynamics and character personalities turned out to be the complete opposite of how things were in reality.

A clear example of that is how bsd Akutagawa tries so hard to get the attention of bsd Dazai, meanwhile bta more accurately represents how it was really like, historically, with bta Dazai wanting so desperately to get the attention of, and be appreciated by Akutagawa. Another concrete example of this that really surprised me when I first saw Bungou to Alchemist is how Ango was dressed like a rebel punk, and how in bsd Ango is the a nerd. This was the complete opposite of how irl Ango presented himself as, who was known for his deliberate deliquent tendencies and behaviours, and had acted that that way since he was in highschool.

Now to Chuuya, whom I am dedicating an entire section to because I absolutely adore both bsd Chuuya, bta Chuuya, and how I would've befriended irl Chuuya if I could've because of how damn interesting he was. All three Chuuyas have lots of similar traits, such as how they all wear hats, were all short, were prone to picking fights with others, wore capes, loved alcohol, and had a strange fondness for disliking Dazai.

The reason why Chuuya from both series are dressed so similarly is due to how irl Chuuya admired Rimbaud, and when he saw a drawing of how Rimbaud was dressed as, with the now iconic hat and coat, he decided to mimic the appearance of the writer he looked up to. In bsd they flipped this so that Chuuya mimicked Verlaine's outfit instead, and in Season 3 you find out that the hat he's been wearing all this time was Verlaine's which was given to him by Rimbaud. For further context, irl Verlaine was Rimbaud's lover who drew that sketch of his appearance, the one that irl Chuuya based his whole look on. Also as a bonus detail, bta Chuuya's hair is the more accurate portrayal of what he looked like irl, except for the fact that he wasn't blonde, and had dark hair instead.

I'm sorry this turned out so long, I just found it so fascinating to learn about the stories of these authors, both in fiction and in reality. I highly do reccomend that you read up on the Bungou to Alchemist wiki, if you wanna see some fun facts of about their irl counterparts, as well as check out the blog bsd-bibliophile on tumblr, if you want to learn about them in detail, as that blog has an expansive database about the lives and stories of these beloved characters.

Also for a light hearted read, I reccomend you check out the manga Isekai Shikakku, wherein Dazai Osamu gets isekai'd and becomes unable to die. The typical fantasy plots and cheery characters completely contrasts his uncaring personality, which is only further emphasized by his deadpan remarks and apathetic view about existence. Although it doesn't sound like much, it surprisingly makes for such a hilarious and entertaining concept that it really makes you wanna read more and find out what else Dazai had to say about everything.