Yes, you can purchase Universal Express Passes at both Universal Studios Florida and Universal Studios Hollywood , provided they are not sold out for the day .
You don't need to return to the front gates to purchase an Express upgrade. You can find them at several locations: Universal Orlando Products Hub can you buy express pass inside universal studios
Buying inside allows you to gauge wait times before committing to the extra cost, though prices may be higher than advance online rates as they fluctuate based on daily demand. Where to Buy Inside the Park Yes, you can purchase Universal Express Passes at