The damage on each appears to have been caused by the same issue -- a population of bagworms, a common native moth caterpillar that chews the foliage of a wide variety of plant species. They are usually a problem on conifers (needled evergreens) like the arborvitae that appears to be pictured in your second photo. (Plant ID is very important in diagnostics, as is more information about the symptoms - when they appeared, how quickly they worsened - and the plant's care history, but in this case, it won't impact the remedy.)

When bagworms chew off the foliage on a conifer like arborvitae, the foliage cannot grow back. If too much of the plant is gone or badly damaged, it would need to be replaced. The cherrylaurel (the other plant pictured) can recover as long as no other issue causes damage, such as over-watering or prolonged drought stress. Leaves cannot heal from damage, but new leaves can fill-in gaps in the plant beginning next year when new growth resumes for the season. Some of the leaf holes can be caused by Cherry Shot Hole Disease, a fungal or bacterial infection, but that does not require treatment (nor would the use of a fungicide spray be able to cure any existing infection anyway). Cherry Shot Hole is a very common condition on cherrylaurel, and anything that keeps the leaves wet (like irrigation that wets the foliage regularly) or a rainy season can promote higher rates of infection. The plant will naturally drop its oldest and most heavily-damaged leaves each year, even though it is evergreen.

For plants that only have a few bagworms within reach, remove the bags and dispose of them. The linked web page above includes management information if you need to resort to having someone apply an insecticide next year. (They will not be feeding any more this year, so an insecticide will not help this time of year.)

Miri

Miri:

It's hard to see the plant clearly from the distance the photo was taken, but overall, no, that much missing growth will not be replaced even if the bagworms are eliminated. If a broadleaf evergreen like a holly or boxwood is trimmed, the older wood where the cuts are made have dormant leaf buds under the bark that can then grow and eventually replace the removed branches or fill-in the gap left by their removal. That is not true for conifers -- with a few exceptions that do not include arborvitae, they do not have those dormant buds so the older wood that is left after dead or damaged branches are cut off is not capable of replacing that lost foliage, so the area will remain permanently bare. If the bare area doesn't bother you and the rest of the plant is spared from further bagworm damage in future years (and if the rest of that growth stays healthy), then the plant will be okay, but it usually doesn't look like a gardener wants in that situation and is therefore best replaced.

Where bagworms turn up can be unpredictable. Very young caterpillars may "balloon" -- catch a ride on a strand of silk that blows them around on the wind -- and be carried quite a distance from where they hatched. They can also be hard to detect when very young, since the bags are quite small and they blend-in well to the foliage they're eating, so they often are not noticed until they are older, in larger bags, and chewing off a lot more foliage. You would need to periodically inspect any vulnerable plants, like other arborvitae in the yard, to see if you notice any bags before an infestation is extensive. If they are reachable, they are easy to pull off and dispatch or toss elsewhere for birds to eat.

Bagworms often start on one plant and spread to neighboring plants, as they appear to be doing in the photo. The defoliated plant is the epicenter of bagworm activity, but we see bags on some of the branches of the neighboring arborvitae specimens as well.

Miri