There will be an "Epilogue" part of development (after V1.0 the main story) where we plan on having time jumps where these kinds of things (breast expansion included) can happen if there is enough interest. Patreon/SubscribeStar is where the voting will be done so that supporters can choose what gets put into the last bit of the game.
Also, obviously pregnancy will included breasts that are enlarged and pregnancy sex is already planned to be put in for each woman impregnated.