Anything that's outsized is much bigger than you'd expect it to be. If you're used to your tiny sports car, it might feel strange to climb into your friend's outsized SUV.
The outsized sequoia trees in California can seem otherworldly, like something you'd find on another planet, especially if you're accustomed to the relatively small, newly planted trees in your neighborhood. And it might seem impossible that your tiny kitten will one day grow into an outsized, twenty-five pound tom cat. Outsized things are exceptionally large.