Regarding "corporate decision making works for designing their characters"
There is no definitive answer as Talus says but let's talk about models from different corporations and over time. In short, putting aside the sexual pigeonholing, the general idea of having a type of group cohesion is most likely considered. That can be groups like HoloX or Niji's "Heroes" cross branch branding but also can just include what games the vtuber excels at like
Moka and
Hanabi from VSPO debuting together. So answering with anything but, "it depends" is disingenuous.
Also, regarding corporate vtubering 3d models, the talents are not adjusting anything on their models so I have no idea why their IRL body sizes are being talked about, fat or not. Debiru has been around for years and Cover didn't nerf Nerissa's boobs, talents adjust the live2d models and the 3d models are the companies responsibility.
Hololive
Hololive started off chasing Kizuna Ai just like everyone else so Sora's initial model was 3d and her early streams were closer to the meta of the time. Her desgin was generic highschool idol. Roboco came second and used a model by 3d modeler kuromaru9
who already had the base model done.
Here she is in 2016 2 years before debut so I imagine that design was convenience though I do remember kuromaru9 being a bit of an "artist" about her design going forward. Miko also came in 3D and is a generic shrine maid, Suisei designed her own and Azki was INNK's project for a
virtual singer hence the futuristic image. Faceless talked about the unused models so there is some consideration about talent matching design. A great example is
Luna and
previous Luna. Considering the design choices for DEV_IS I think it's clear that Cover is incorporating more talent led design choices, the characters feel more like the talents right off the bat from Raden's fan to Chihaya's earings, their interests are on display.
Niji
Niji's unused models got talked about but for fun this
Full Metal Alchemist looking fat fuck also became a meme for a bit. Also, looks like
many designs were auditioned for. Of note, only Oliver and Ha yun got picked from this.
If you look at their early designs there is a large variety from normal to weird with Hanabatake Chaika, Dola, Joe and Shiba being some good examples that suggest talents had a hand in what character they wanted (or tried out for). Shiba is a furry so that's another point for that. Recently other then Lunlun, who Niji had an audition for someone to be a mascot character, the designs are more "normal".
VSPO and more
Yuuhi from VSPO requested Ui to design her. Ui is fickle so that was a major win for Yuuhi. Unfortunately, I know jack all about the other large JP's: 774, Re:Act, Aogiri Highschool or others but we do have NoriPro's rebranding to look at. Basically, most original members left and she brought in "
creators" so artists and video editors and such. That's another way to recruit and there is no specific theme for the members -
https://noripro.jp/#talent.
If all that doesn't seem like it matters for EN design wise then I request a company that doesn't follow JP corpo design practice and standards. Maybe if they are doing something different like VOMS (artist pet project),
Camoni, or this small indie
but there isn't one.
The only other different design choice is the 2.5d vtuber but it's more about the premise of the channel then aesthetic:
Urara and KAF are two great examples where they show IRL body but not face blending the immersion.
An aside, is there a reason I can't search Scuttle's posts anymore? It's the best way to remember Niji history so that would be nice to have fixed. My issue is that I want to advanced search their posts and the only member I get is Scuttlefuck