Q.Fertilization of holly trees.
I have two approximate 4 foot tall holly trees that have loss approximately 50 % of their leaves over the winter mostly at or near the bottom of the trees. Would using Holly Tone at the bottom of the trees and watering them now bring back the leaves? Some of the branches are showing new growth at the top more than at the bottom.

Yes, use your Holly Tone fertilizer. And thank you for mentioning it. I wasn't familiar with it, but I just reviewed the label and I really like the composition.
Consider mulching the soil surface to help retain soil moisture through the summer, enhance soil organic matter content and biological activity.
This article may help you with general care and in assessing the leaf drop condition.
https://www.gardeningknowhow.com/ornamental/shrubs/holly/holly-leaf-loss-in-spring.htm