We don’t really want to see an elephant explode, unless it’s in colorful yet fictional graphics from Kurzgesagt. In other words, we will only look at how it’s theoretically possible.
This video explains the difference between how a small animal, such as a hummingbird, and a large animal, such as an elephant, deal with the physics of life.
Animals of different sizes have to balance energy, metabolism, and heat transference in a way that’s optimal for their size. You can’t just take a certain species and change its size without changing its design as well, despite movies like Attack of the 50 Foot Woman or Honey, I Shrunk the Kids.