I used to be a T-shirt guy. I actively sabotaged any valuation people might make of me based on appearance to force evaluation only of my technical skills. That worked fine for a couple decades.

Now I work hard to maximize the value of the connections I make and the overall value I can provide to others, which is not always entirely technical.

I wear a suit and tie to all meetings now. I wear the same to every occasion when I am actually in an office and even sometimes over Zoom. It sets me apart and shows my interlocutor that I value the meeting and respect his or her time. It sets a tone and I find it is well worth the effort.

Amusingly, I spent those first two decades working for the DoD and there is definitely a dress code and an aversion to wearing suits for some civilians.