Can you improve arm strength?

Optimus Prime said
QBs are criticized for their lack of arm strength

He can't make this throw, or that throw

His deep passes float on him

Is that something that can be greatly improved in the gym/practice or just slightly, or not at all?

If there is a lineman who just needs to get stronger, no one seems terribly worried about it, just work out and get stronger

But I've never heard arm strength talked about like that before

I think once you’ve squeezed out all the accuracy and power gains from proper body mechanics, any further arm strength/speed improvement is unlikely at the next level. I was trying to find a reliable source for when a pitcher’s velocity peaks to use as a comparison, a few unreliable looking sources say that pitching speed starts dropping around age 26 by one MPH per year.