You have arborvitae shrubs or trees. Arborvitae are pretty adaptable trees, but they do not tolerate fall droughts well. We had a severe drought in parts of Maryland last fall. There is nothing you can do now about that.
Prune out the dead branches, back to live green wood. Be alert to future droughts in the fall. They can be deadly. Water well. Do not let these--or any of your broad-leaved evergreens--go into winter in dry soil.
Emma, Thanks so much.
Stay safe, Don
Sorry l meant Ellen. Best, Don