Yes it's true they can have an effect, but the amount needed is somewhat dangerous for the liver, for one licorice root (not the Lollies) used as an anti androgen is actually poisonous, then there's black cohosh which is bad for the liver in high doses.
Not that I make any claim that they work, because I've never used em, you could try bovine supplements, because I can definitely say they are much safer then some phytoestrogen, that will likely clog the hormone receptors, which may lead to some hormone deficiencys and they can n do compete with naturaly produced estrogens, so basically I'm saying there to dangerous in the high doses needed for significant feminization, in comparison to HRT, plus phytoestrogens are more like estriol not estradiol, estradiol is the one that you need to feminize.
Good luck.