Hope it's okay to chime in, I was just reading and this is such an interesting question. I'm going to have to think about it for myself over the next few days!
As a cis woman (well, really when I think about it for any length of time I feel utterly agender, but I am not bothered by being called she so I've just never done much public exploration of it and have largely kept to traditional feminine aesthetics) who doesn't often think of gender as relevant in a euphoric, intentional, joyous way, just in how I'm perceived by others, this is a hard and important question.
Recently I've been getting an unexpected thrill from a bunch of people in forums for my hobbies and side projects online assuming I'm a guy from the way I write and responding to me with things like "enjoy it, bro," "appreciate the love, dude," recommending things to wear on account of them being "super masculine," and so on. I don't really know what this is, but there's an elicit sort of thrill to feeling like "one of the boys" despite an icon or pronoun or profile picture revealing I'm not if they pay attention. I know this isn't about self-expression but rather something in how people address me, and probably rooted in feeling respected on the level of a man in male company, but it's something interesting I've observed lately.
There's also something that feels really right to me about dressing a bit like a dorky middle aged man from some Silicon Valley startup circa 2003. I'm wearing my favorite shirt right now, a brown long-sleeved collared shirt with buttons that go halfway down, and big non-fitted, not-irritating-my-pelvic-pain jeans with a big bold wide brown belt. I have a few of my dad's old plaid button ups I've stolen that I also really love. There's something about the loose-jeans-and-dorky-men's-buttoned-shirts look that feels so right in the mirror. I'd like to find more clothes like this. It just feels really fun to me.
Also, earrings. The weirder the better. I have a pair that are giant shiny red plastic lobsters that I don't wear enough. Right now I'm wearing some that are dainty glass oranges my boyfriend surprised me with. I also have small wide gold hoops that I love a lot. I often forget about earrings for a long period because my ears were super badly pierced at Claire's as a kid and I basically have to re-pierce them every time and one regularly bleeds so sometimes when I overdo it I have to stop wearing them for a couple days and then I forget. (I know, I know -- I should get those redone. Typing this out is making me realize that lol.) But then I come back to them again, like today, and it makes me happy.
I think I'm going to cut my hair tomorrow. It's waist-length, and this is my second time growing it out to at least this long and then chopping it all off and donating it. I basically always had super long hair growing up and am really reckoning with it; my hair is super fine and tangly and a nightmare to manage even when it's shorter, and I've pretty much never liked it, but felt like I needed to hide behind limp long hair as a symbol of femininity to excuse what I think of as an ugly and unfeminine face. As if beauty, and traditional feminine expression, is something I owe the world just for being here.
I think I'm going to go for something around the shoulders -- in many ways I feel like that's one of the most attractive hair lengths of anyone of any gender. It makes me think of warriors, of all the tousled and messy wavy hair of men and women alike in Lord of the Rings, of brave Ghibli movie boys and girls, of knights and Joan of Arc. There's something that feels really powerful to me about that sort of haircut motif in this genderless mix of really brave, adventurous, persevering people and characters, because that's who I want to be. I have always hated my hair and thought it looked bad most of the time at any length, so I really hope this turns out well (or at least okay) and leads me to explore this sort of gender expression question for myself more.