Games

I think that there are other angles to look at Sheik as besides it ("it" being the act of taking up a masculine persona) just not being trans representation. I generally think stories where women pretend to be men to accomplish some aim (e.g. military enlistment) have a progressive bent because the fundamental conceit of them is that society puts women in a dehumanized position as being less capable than men, as "imitating men" when they try to act as human beings, so by hiding their sex they circumvent the obstacle of this bigotry and disprove its basis by accomplishing whatever they are trying to accomplish "as a man."

While the persona of Sheik wasn't made of this purpose in a direct in-universe sense, I would argue that it at least serves it on a more meta level by showing the player someone who is highly competent to judge on their own merits before they are revealed to be Zelda.