Can I have rectangular grid workspace in Ubuntu 18.04?

Problem description

I really like the 2 by 2 workspaces in Ubuntu 16.04. But it seems I can only shift workspace up and down.

Is there a way to achieve this?

What I have tried

Tried the GNOME extension called Workspace Grid (suggested here: Can I have 2x2 workspaces in GNOME 3?), however, it does not work because when I tried to install it, I cannot find installation extension in the GNOME Tweaks.

The option to install GNOME extensions using GNOME Tweaks is removed from last few versions of the application. But you can simply install and manage extensions from their official websites. To do that first install the chrome-gnome-shell package by running the following command in Terminal

sudo apt install chrome-gnome-shell

Then visit https://extensions.gnome.org/ using Firefox or Google Chrome, the website should ask you to install one browser add-on/extension. Install it.

Then go to the extension's homepage, you'll be able to install the extension just by toggling on the button at the top-right:

Alternatively, you can manually install extensions following this answer.

The Workspace Matrix extension is better than Workspace Grid in my experience. It's based on Workspace Grid, but fixed to work properly on Ubuntu 18, including thumbnails and some other weird kinks that Workspace Grid has (the grid was randomly changing size as I switched between workspaces, for example):

https://github.com/mzur/gnome-shell-wsmatrix

Install it by searching the Ubuntu Software Center for Workspace Matrix: