Hey there Makenzie,
Welcome to planDisney and thank you for your question! I'm thrilled to hear that you're planning to ring in the New Year at the Happiest Place on Earth. This year is flying by, so I'm certain your trip will be here before you know it.
I'm happy to share that your
theme park tickets grant you entry for the full duration of park hours on a given day - even if the
park hours happen to creep into the next day as is the case for New Year's Eve. Therefore, you would not need to purchase additional tickets to stick around past midnight.
While this is likely to be a busy day in the parks, you're going to get to experience all the Disney Magic mixed in with your New Year's celebration. While the official park hours haven't been released yet, in previous years, Disney California Adventure Park has been open until 1 AM and Disneyland Park has been open until 2 AM. There has also historically been a pretty epic fireworks show to ring that kicks off at midnight.
As you get closer to your trip, I'd recommend keeping an eye on the
Disney Parks Blog for all the official details of what to expect during your visit. Thanks again for your question, Makenzie!
Have a Magical Day,
Greg