This one is a fantasy experience, so it will not change your body in real life! Feel free to explore without having any extra feminizing effects to your body.
You have a magic bra that appears on your bed. When you put it on, you can morph into any female that you want to, and feel/see her real boobs on your chest. Your whole body will change to look like that woman’s, but especially her chest. Your boobs bounce, and you love the feeling of it. You feel pleasure like she does. You orgasm like she does.
The sensations of pleasure are so wonderfully powerful that it creates the very real feelings of big breasts on your chest!