A simple example of this might be a haircut. Whether accurate or not, a mohawk often signals something to other people (and sometimes signals something the person that wears it, like "I may be ties down with more responsibilities, but I won't let that define me").
I like to think most my clothing choices are made because of practical matters such as comfort and fit, but even within my normal range of jeans to shorts and t-shirts to polo shirts (and maybe the less formal button-up shirt), there's definitely things that fit that criteria that don't feel like they fit how I think of myself. And that's as a man, where I think expectations to do with style and clothing are much simpler.
For what it's worth, they develop a loyal following.
The same with clothes: the choice of textures say something about you, the choice of cuts say something, the choice of colour the same. The thing is: the clothes you wear need to resonate with you to become part of your expression.
It's not that your clothes = your personality, but the choices you've done consciously will tell someone else about you, the same as looking around your book shelves at home. The thing is: you need to care about you are wearing for it to become something expressive.
With my clothes I can signal a lot of stuff to others that are into the same things I am, I can signal hobbies, I can signal that I care about a particular type of material or cut, and so on.
If not then you are just being practical and wearing what is expected from you, nothing wrong with that but don't judge and put others down because they take this more into consideration than you do.
It's just a cheap way to signal something that you might or might not be, and only superficially at that.
But be realistic. Someone that wears all black has made a choice just like the person that is always fashionable with lots of clothing. Some beard and hairstyles take more work than others. These are lifestyle choices people make. Someone knowing how to do 20 hairstyles to get their hair off of their neck decided to learn that instead of something else. A man with a complicated beard style probably spends some time daily on it to keep it up. A person with nails half the length of the fingers they are attached to probably eshews some practical things simply because the nails are in the way. A person that wears traditional clothing due to religion probably isn't a good candidate to date me.
I understand that being poor might make it so you don't have a lot of choices in these things. I've been there: My look was basically whatever I was forced to wear to work and whatever I could find at thrift stores. At the end of the day, though, I still had choice -and to discount what these choices tell others about you is, in itself, dense - as is discounting that humanity often makes snap judgements based entirely on how things look.
Personality is expressed through choice of cut, material, and color of cloth?