Q.Elephant ear indoor plant
Instead of the usual large leaves, it now has more smaller leaves and they are all drying out or turning yellow. I sprayed the plant with some Miracle Gro disease and mite control, as I noticed some white powdery stuff on the trunk area. I need to save this plant.

Check the watering of your plant.
Elephant Ear needs high humidity and you can run a humidifier in the room.
A bright sunlight is needed, but avoid direct sun.
Neem Oil is a good treatment for pests.
This may be Mealybug on your plant.
Here are some links with more information.
https://www.gardeningknowhow.com/ornamental/bulbs/elephant-ear/growing-elephant-ears-indoors.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/mealybugs-control.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm