Been thinking a lot about Transfem Sanji and how the crew would react to her, if the egg came back cracked post time skip, so here it goes:
Luffy: He doesn't notice. Pronouns and gender are a weird shit to him. Sanji has just asked to be called a she now. Fine, whatever, she is still gonna be cooking, right? Doesn't fully realize until Nami kicks some sense into him.
Chopper: "Why didn't you tell me?! Now I have medical records to update!" Runs to do so. Also, is three minutes saying sorry every time he missgenders her on accident.
Usopp: "his pronouns are she/her". And gave Sanji a water spray to use with a label "Use when missgender" to encourage the crew.
Brook: "May I look at your pant-". Nami kicks him. But after Sanji shows cuz he has this pervert solidarity with Brook.
Nami: She would let Sanji on the girls room with promise to not peek while she changes (She peeks). Would help her go shopping (Zoro gets to carry bags) and try to find one of those fake news photographer that actually sell their photos to the marine so Sanji can change hers in her bounty poster.
Robin: She would totally smile at her, like she knew something. She could kinda guess the egg. She shows Sanji some books on other cultures that treat gender differently from what he knows. Robin knows coming out must be scary so she smiles more to Sanji as reward, sometimes calling her "dear" too like Sanji does. But only sometimes because Sanji might be a girl now, but nosebleeds keep coming.
Franky: he would Immediately update the girls room to fit Sanji. He takes a soda away from himself every time he missgenders Sanji, to try and stop, even if Sanji has told him there is no need.
Jimbei: He didn't knew Sanji much before she transitioned, so he just assumed Sanji was a girl with short hair back then. But when he finds out... Like, he is half fish, and he knows Iva, so not the weirdest shit he has seen
Zoro: He would keep messing up with Sanji, but has two voices in his head. One is the old Sanji, telling him to not pick a fight on a lady and the other is Kuina, asking him if he is not fighting Sanji because he thinks girls are weaker. Its fucking annoying. Plus Sanji has found out how easy is to bother Zoro now with the "Sexist card". Like "Cook, im hungry,make lunch" "Oh, right. Cause im the woman and we belong in the kitchen, right?" Or stuff like that that makes Zoro's brain shortcircuit because he really doesn't give a fuck about Sanji's body or gender, she is still the shitty cook. And even if he doesn't realize, the fact that he refuses to treat her differently calms Sanji a lot.