Most fursonas do wear clothes. But putting aside the aesthetics factor and focusing more on the practicality-- would a furry anthro in an anthro society wear clothes?
Focusing solely on mammalian anthros with fur. Well, they have fur, so temperature regulation and the elements aren't really reasons to wear clothes given that they have natural, furry clothes already. Wearing clothes on top of that might be too warm, especially in the summer.
The thing I'm wondering is, would anthros figure out to make clothings themselves? And if they do, how would they look? Having their body completely covered in fur might make shirts and pants irrelevant, which means they might never develop them in the first place. I suppose other articles of clothings like armbands, headbands, etc would still exist, and so would practical items like glasses or watches.
Of course, clothing serves more purpose than just covering bare skins. They serve aesthetic purposes and shows our identity. For example, police anthros might wear some sort of stuff to distinguish themselves. And much like humans, anthros would probably have a culture around clothing, but how their clothing would look and how much it'll cover is the question.
Would most anthros only wear head and armbands? Maybe just something to cover their bottoms and nothing else? Or would they wear clothes similar to us?
Furthermore, different animals have different fur with different thickness, length, shapes, forms, etc. These different furs require different clothing. Anthros with thicker fur may wear less clothing than ones with thinner fur. Even more, different anthros will have different body shape and size. Clothing for rabbit sonas may not fit bear sonas.
Anthros might have different size standards for different species to account their differences. Imagine how hard it'd be to manufacture all the different variations, though. Any clothes store would have to take into account multiple species and multiple sizes for that species.
Well, I think that's interesting to think about.
I would say yes but in most everyday applications it would be more for style and asthetic rather than for warmth, though that also depends on the length of their fur and the temperature. Obviously in a very cold place where it gets bitterly cold they might wear warm clothes in addition to their fur to help stay warmer, or if they're a species with shorter fur they would wear warm clothes to stay warm in general. Clothing would also be important for protection in industrial environments as a form of protection, or to prevent contamination from fur.
As for how it would fit I imagine that clothes would have to be custom designed for each species, but they might also have the option of different sizing types that can work with different groups of species, though they would be baggy on some species (there isn't a way to make that work without custom designing for each specifically).