Zoe is going to be a weird balance champ for a while
She does have a higher skill floor and skill cap than most champs, and given that she was just released, she is going to have a low win rate. An abyssal win rate IMO. Which could mean that Riot could buff her.
That said, her Q damage is huge, and if she lands a E (her sleep spell) and then a long range Q, she can legitimately one shot a back line. (her E makes the next attack/spell deal double damage)
Her laning phase can be heavily influenced by RNG. Took some damage? A minion could drop heal/redemption. Need to back? A minion could drop ghost/TP. Want to go in an trade? A minion could drop gunblade/protobelt/ignite/exhaust. Or none of this could happen. You could be getting smashed and get smite. Its very RNG. In addition to this, Zoe can hold onto those shards for a long time, 60 seconds.
So all in all, Riot is going to have to effectively balance an extremely high skill floor/skill cap champ that brings incredible RNG to her matches