They don't do what would be a "drink package" exactly. You purchase a Passport and you can get 7 drinks in Skyline over the 7 night cruise. I believe it may be only specific drinks, not any drinks. But I could be wrong about that.
LaPiazza is another of the bars onboard the ship. I don't know of any bulk purchase options there. But there could be one now.
EDIT: regarding the Skyline Passport, I found this:
Skyline Passport
Skyline on the
Disney Fantasy offers a
passport card for $59. The
Skyline Passport card entitles you to seven hand-crafted martinis, themed to each to the cities of the seven rotating European skylines. Breaking this down, you will get seven martinis for the price of six.
https://disneycruiselineblog.com/2012/08/a-guide-to-drinking-on-a-disney-cruise/