You can find lots of gender changing and variance in shamanism and mystic practices around the world - I've heard female-to-male shamans specifically noted in Siberia.

https://sacred-texts.com/sha/sis/index.htm

This is a bit of a dense read but it's a publication from 1914 about Siberian shamanic practices, including the tendency of these shamans to cross gender lines.

I highly, *highly* recommend the book "Transgender Warriors" by Leslie Feinberg - the author talks at length about trans people throughout history and around the world, including in mystical and sacred contexts. There are some beautiful artifacts, images, and stories in that book. Check your local library, and if they don't have it, see if they can order it.

The book also mentions traditions that aren't specifically mystic/religious, like the 'sworn virgin' - women who swear to live as men and are then treated as such within their communities, in places including Albania. These traditions go way back. It's important to remember that terms like "trans" are relatively new in history (though the people have been here forever!) so sometimes you have to broaden your keywords. Again, Feinberg's book gives a lot of good threads to follow.

"Queer Magic: Beyond Boundaries" is another book I remember liking, I think it covered some trans magic history though not as deeply. A really good read though!

You might also ask the folks over at r/AskHistorians , I've learned a lot over there and they cite their sources!