Is it permissible for the fiancée to wear a dress that reveals the arms, upper chest, and lower legs in front of women at the engagement party?

There is no objection to wearing the aforementioned dress as long as it is among women, because the 'awrah (intimate parts) of a woman in front of another Muslim woman is what is between the navel and the knee, as Al-Baghawi mentioned in his interpretation of the verse: "Or their women" (Quran 24:31), meaning that it is permissible for a woman to look at the body of another woman except for what is between the navel and the knee, similar to a mahram man.