Holly (?) Tree dying
I have what I am sure if a holly tree, although it does not look like any I have seen online, and it seems to be dying. The crown has many dead branches and the entire tree is missing a lot of leaves. The leaves themselves seem fine, but I did notice what seems to be spider webs in the many of the branches.
This is an American holly, a beautiful native and extremely old. The dieback suggests a root or trunk problem.
Spider webs would not harm your holly, but there could be a more complicated insect problem. If you can attach photos to a reply of close-ups of the webbing, we would be able to be more specific.
Unless your holly is dying of old age or a root problem, it may be able to regenerate from the root if you have to cut it down. It has deteriorated so far that it doesn't look likely it would be able to recover.