Are you talking about cross-dressing people or transgender people?
Because I'm sure all of us know some transgender people at work. It's just that we never suspect that they are transgender, because they are able to pass very well for a person of their changed gender.
For example, I have a friend who is a trans-man, but if I didn't tell you, you would never guess that he was a woman at birth and till early adulthood.
Because of breast-reduction surgery and hormone therapy, now he has a full-beard and mustache, and is well-built from working out at the gym. So if you met him at work today, you would think he was always a man from birth.
I am talking about cross dressing people not about the transgender.
Very few. There aren't any policies for it as such, just matters how accepting the company is.
Some straight guys like makeup and nail paint as well, but not every company will have employees who are chill about it.
Piercings and tattoos are also a big no in many companies