Elephants have very high HP.
You need to lure them near to your TC and then garrison the luring vil to de-aggro them. Lure both of them next to the TC.
The garrisoned vils will take some time to heal. In this time, the two Elephants will mate and produce a bunch of calfs, each with around 100 HP and 100 food. You can take them easily because they don’t fight back.
Of course, in some cases, because of RNG, the big Eles will try to go back. In that case, take a sheep vil and attack them again to make them come back. This way, the Eles will keep making calfs and providing unlimited food.
Hardly anyone tries this because of the time it takes for the calves to come.