you have to take drugs in chapter 7 to get the options. the variable "v14_lena_drug" has 4 states (False),(1),(2) and (3).
early in the update (in the prologue so to speak) ivy offers lena to take drugs, causing state (1). that is needed to get to state (2) later on, as otherwise you won't be able to. from (2) you automatically get to state (3), which has most likely the biggest impact on your playthrough (as it is also changing the anthony scene i mentioned earlier), but the other states also are affecting your scenes. you can however get to state (3) also by going from state (1) by a choice later in chapter 14, or just by just having done drugs in chapter 7 and ivy likes you more than 3 points, also by choice.
holly has absolutely nothing to do with it, meaning neither "not dating", "in a relationship with lena", "slut holly" nor "throuple holly" has any effect on your lena's drug consumption.