Where do I copy plugins in SU2016, there is no plugin file under sketchup
instal fresh copies [that have the .rbz file extension] using Preferences >> Extensions >> Instal Extension…
john
There is a Plugins folder for SketchUp but it was moved a few versions back into User/App Data/Roaming/SketchUp/… It’s a hidden folder so you would need to make it visible first. As John said, though, you should install fresh copies of the plugins/extensions instead of copying the old ones.
See this Help article and the many links within it…
Installing Ruby Plugins (Extensions) — SketchUp Help