In regards to the Hundred Years war, I often hear (from questionable) sources that the English Archers had a sidearm and maybe something like a padded jack. I find this amazing because the English have had some decisive victories over the French , shouldn't an archer have a pretty good chance at taking over the armor and weapons of a knight?
Would there be plate-armored archers after a few victories?
To answer your question directly, no. While taking weapons and armor off the deceased was common enough, an archer has exactly zero want for heavy armor.
First, they are virtually always in the rear and protected by other soldiers.
Secondly, the armor, no matter how well fitting, would reduce their mobility enough that they would be less effective. The archer's best defense was mobility.
To expand, it's entirely likely that some leather armor, or chainmail may have been "borrowed" here and there, but plate armor is a custom made product. If it doesn't fit you near perfectly, it's a serious handicap.