Sorry, because of this licence thing PC/Console, I can’t reply directly.
It does have consequences for your existing characters: it will unlock all the Lillith Statues for you, which is account wide. If you don’t care about that or have already done it, then it has no effect on other characters. I already had all statues, so there’s no effect for me and have a parked sorc in Eternal, that I’d likely never play.
It’s time limited, so eventually it will no longer be offered as an option.