well the potions only change the cum output, i.e. fertility girls have more cum leaking, while barren barely has anything to leak.
The only other variation is based on outfits you can buy from the tailor.. and the only character that has a missable outfit scene so far is Victoria (the mayors wife)
at some points potions allow a scene to continue (2x fertility potions to get the vampire sister 4 some or energy potion to get both Caleah and Ziva, but those are repeatable)
there is a potion that allows scenes to be viewed, even if you didn't trigger them before.
for example save Mia from the Goblins so she won't be raped. there is another one for Calea that you might want to avoid in order to be her Hero.
have a potion in backpack and head into the direction those scenes would trigger and interact with the irwish
