Ivy offers Lena drugs not once, but twice. Both times she did it was at the location where Ivy would need to spike Holly's drink. Just because she offers drugs doesn't mean she is going to spike Holly's drink that is true, but it doesn't mean it is outside of the realm of possibility. For you see Ivy may have more loyalties to Lena than she does to Holly as Ivy & Lena go way way back so she may have given Lena the choice, and not given Holly the choice. Because Ivy may feel Holly is a "bit of a square" and "Won't accept drugs." so she pushes that boudnary for her as a "Good Teacher".I'm sorry but this is bullshit. Ivy offers Lena party drugs once. If Lena refuses, next time Ivy takes drugs herself the player has to make Lena ask for them (and burn a willpoint on it) because Ivy won't make the offer again. Furthermore, there's absolutely no basis to presume that because Ivy offers Lena's to choose if she wants some party drugs, then she'd just drug Holly without her knowledge -- Ivy clearly shows she understands and respects consent.
This game isn't GGGB and Eva has stated it's not going to be like GGGB in terms on content, but much more grounded. So if even in the "wilder" previous game you had this sort of content upfront and in the open, there's really no reason other than wishful thinking to expect this, much more tame game, will have this sort of shit cranked up even further, by making it a completely unannounced asspull.
I think it may be best for you to drop such hopes, or you'll only find yourself disappointed.
It's obviously not GGGB, but a lot of elements from GGGB are also in ORS. There may be similar incidents and things that seem to cross over a bit. The fact that Jessica exists in ORS is proof they are in the same universe. In universe where Arthur will get Ashley to Spike Iris's drink it's well within the bounds of reality for Ivy to Spike Holly's drink.