I’ve got some questions before I can answer.
1 Will you already be checked in to your Disney hotel?
2 Did you buy your tickets with the park hopper option or are you stuck with one park, one day?
3 How many days is your ticket for?
So, if you are already checked into your Disney hotel before you head to the Studios, and you have a 7 day ticket, preferably a park hopper so you aren’t confined to one park on any given day, and have your heart set on getting in a couple of hours in a park after a day at Universal, yes. So long as you you’re OK with the limited QS choices in the Studios.
If you answer no to any one of those questions, forget it.
I say a 7 day ticket because you say you’ve got a 6 day package, which I assume is 6 nights, 6 days worth of food, and 6 days worth of tickets and further assume you’re going to want to squeeze in some time in a park on your last day before you head back to the airport (or hit the highway). So, you’ll need to add a 7th day, but the difference between 6 and 7 days isn’t that great. I also strongly recommend upgrading base tickets to park hoppers because if you don’t you’re locked into one park that day, and depending on the day, that park could close pretty early, be too crowded, or you simply want to see night time entertainment in a different park.
Don’t worry though, even with the base ticket, you can enter and re enter that park as many times as you want or need, you just won’t be able to go from say, AK to MK on the same day or Studios, which often closes at 7, to Epcot, which always closes at 9. Plus, you need to factor in Extra Magic Hours.