cd && cd Downloads
wget https://launchpad.net/ubuntu/+archive/primary/+sourcefiles/plank/0.11.89-1/plank_0.11.89.orig.tar.xz
tar xf plank_0.11.89.orig.tar.xz
cd plank-0.11.89
Now for compiling and installing Plank;
./configure
make
sudo make install
Now you have what is needed to zoom in Plank and can therefore reinstall the Plank libs.
sudo apt install --reinstall plank libplank*
Two files need to be edited before you can get the zoom effect, copy/paste;
This guide will show you how to run multiply planks on elementary OS. It can be rather useful if you have more than one monitor.
Open the terminal and copy/paste:
plank -n panel-two --preferences
In this example I use the word panel-two, but you can call it whatever you want. You can call them panel-one, panel-two, panel-three etc.
Now setup your new panel.
When done, go to System Settings. Click Applications and pick Startup.
Add the following command;
plank -n panel-two
Now log out and log in. You’ll now have an extra plank.
Enjoy! ^_^