Transgender aunt

So my baby will have a transgender (m-f) aunt and she’s already said that if our baby is a boy (which he is) that she’s going to buy him Barbie dolls and other stereotypically “girls” toys.

I’m not at all against this if he likes barbies and stuff like that because I believe children should play however they want to, but what if he doesn’t? If he didn’t like that sort of stuff and she got him barbies for Christmas how would I go about explaining to her that she shouldn’t do that in a sensitive way? Mind you, she takes EVERYTHING offensive and discriminating against lgtbq. Even when we called her to tell her we’re going to have a son, she said you really shouldn’t say that just in case they aren’t a boy. I’m sorry, but until my son can talk and tell me his pronoun preference I’m going to say HE is my son.