Most experts in gender are trans. This is a statement that may seem shocking, until you subject it to some scrutiny. Gender is not taught with any depth or rigor, to cis people, outside of specialist degrees or extra credits in college. Instead, they learn gender as rules.
"Boys do this, Girls do that. Men do this, women do that. This is a man color. This is a woman color. This is a girl style, that is a boy style." They learn gender as long, endless, linked lists of rules. For most cis, their engagement with gender is entirely superficial.
To be trans is to be *forced* to become an expert in gender, simply to survive. To "pass" during transition is to subject yourself to total immersion learning, with incredibly brutal pass/fail gates. You are required to learn and internalize how gender is read and performed.
It begins to become incredibly obvious and apparent to you, how you are being gendered in the minds of the people who interact with you, and over time and through experimentation and adaptation, you learn what changes to your demeanour, appearance, and style affect that gendering
You learn which ways of answering the phone get you a "hello, sir" and which get you a "hi, ma'am." you learn what colors and styles and ways of moving get you read the way you desire to be read, and treated the way you desire to be treated.