What type of "pine"? Usually not as "pines" don't sprout in that manner along trunks, tho I've seen rare examples of certain species that might do it. However, if shade-released, existing branches could grow outward and downward to some extent.

I think it's actually a Eastern red cedar and a box elder that's getting big blocking the sun. They were already there when we moved in and the red cedars were nice and full but there was this little box elder that has gotten bigger and bigger blocking the sun and the cedars are losing branches. I looked up the trees on my plant identification app so i think thats what they are. I will look for photos and post them

This is in summer look how big the box elder is blocking all the sun

Your "pine" trees seem to be Norway spruces, but not entirely sure. Whichever, just me perhaps, but I wouldn't hesitate (much) from severely cutting back a boxelder.

I've been hesitant to cut it because it's pretty in summer and provides lots of privacy, but if the spruce trees or cedar not sure would fill out again I'd rather have those

A boxelder would not be hurt much by a significant trimming, it would just sprout out more.

I've watching numerous types of conifers grow for the last 30 years and can say with confidence neither spruce or pine will regrow the branches or needles once they are abandoned because of competition (with minor exceptions). For all trees it's a race to the top and they will focus energy to grow vertically to get to the top for sunlight. Conifers are the planets original tree species and the tallest in America. Redwood, Douglas fir, Sequoia and cypress are all conifers.

25 years ago I trimmed lower branches from pine, blue spruce and Norway spruce up 10+ feet and they never grew back. I only witnessed a few attempts in all the years and remember because they were oddities to me (and the exception). But Spruce does hold their lower branches better than Pine, but pine will abandon lower branches even from it's own competition from above because there is better opportunity for sunlight at the top and where they focus growth.

Your trees are spruce. The difference is spruce grow individual needles and are very stiff. Pine grows needles in clusters. It's very unlikely the abandoned branches will ever grow back. If they were pines at least a quarter of the trees from the bottom up would be just trunks.

Thank you good to know