In general, mosses or lichens are not harmful to trees, they are just a natural part of this climate's plant life and the life cycle of the local trees.

Excessive moss or lichens can indicate a tree past its prime, more due to old age than harm from moss.

Would have to know more about what kind of trees you have before advising they be cut down.

Moss and lichen grow on everything that doesn't move too fast. They do not harm whatever they're growing on. Deciduous trees and ones that are not very leafy anymore get a lot because the mosses and lichens get more sun on them. My teak deck chair is positively fuzzy with moss and lichen.

Thank you so much for the information!