Is "bosom" a gender-neutral word? Can we use it to describe the chest/breast of a man?
Eg: She embraced his bosom with passion.
Bosom has two related, but distinct meanings:
1 a: the human chest and especially the front part of the chest
// hugged the child to his bosomb : a woman's breasts regarded especially as a single feature
// a woman with an ample bosom
also : BREAST
// a woman's bosoms
https://www.merriam-webster.com/dictionary/bosom#h1
There are also some figurative uses of bosom, which, not being literal, can apply to males - "a story you will take to your bosom" - or to non-human things - "the bosom of her family".
BUT, none of these uses is especially common. My very unscientific sense is that the "woman's breasts" meaning is more common, but it still sounds old-fashioned.
If I were an English learner, I would try to be aware of the meaning of this word, but I would never use it myself. As a native speaker of American English I have only ever used this word jokingly to sound old-fashioned.