Kinda complicated question because at first phytoestrogens we can found in soy, garlic, peaches, nuts etc is kinda minimal ridiculous amounts and have often time antiestrogenic effects on women (proven to reduce estrogen levels in menopausal women) and also their anti-oxidatives effects (e.g Flavonol => Quercitin, Stilbenes => Resveratrol) are in larger quantities
Also you need to have the perfect gut microbiome to even convert the phytoestrogens compound called Lignans into Enterolactones and Enterodiol, 2 hormones mimicking or simillar to blood estrogen
So imo the anti-oxidative effects are more "powerful" that any estrogen-binding process
I don't recommend to eat soy ofc but you aren't gonna grow boobs from it, there is more factors like obesity who spikes estrogen and steroid-users fucking up their estrogen management process
Also overall growing boobs is purely genetic. Just like balding.