Like everything else on Linux, terminal can also be customized to fit your preferences.
To change the design of terminal, you don't have to download an extension or theme to do it.
In Ubuntu, and any other Linux distro, there is an option that allows you to change the transparency of the terminal.
By default terminal on Linux it's not transparent, you need to enable this setting manually, and set the transparency level that you like.
In this tutorial, you will learn how to make your terminal on Linux transparent
Step 1 - Launch Terminal
CTRL + ALT + T is the key combination that you can use to launch Terminal on Linux.
However, you can also launch terminal by using GUI.
Open "Activities Overview", and search for "Terminal" on the search box, and you should see Terminal icon as shown in the image below.
Now to launch it, simply click it

Step 2 - Make Linux terminal transparent
Once Terminal is launched. Click to "Settings" button

Choose "Preferences"

Next, click to profile name

Once you are in the profile section, click to "Colors" tab

Now, you need to disable "Use transparency from system theme" setting. Simply untick the box

Once you have disabled the setting above, you need to enable the "Use transparent background" setting. This is the setting that will make terminal transparent.
When you enable this setting, the transparency slider will also be enabled. The transparency slider allows you to adjust the transparency of the terminal.

And the transparency slider should be enabled now. To adjust the transparency of the terminal, simply move the slider to the left or right.
Moving left will make terminal less transparent, while moving right will make terminal more transparent.

And now you should have a transparent Terminal

Conclusion
In this tutorial, you learned how to make terminal on Linux transparent.
We used Ubuntu 23.04 on this tutorial. However, the steps should be valid for other linux distributions.