Enable GD support on PHP 7.2 in a Ubuntu 18.04

I need to enable GD support on PHP 7.2 in a Ubuntu 18.04 installation and I've found this solution on the web:

sudo apt-get install php7.2-gd

Since I'm not an expert and I'm worried about the already running configuration files, I have to ask if this command

• will make a brand new installation of PHP with GD extension included

or

• will just add the GD extension to my existing PHP installation and I don't have to worry about any configuration file changes

This command will install the GD extension only if PHP 7.2 is already installed.

If not, it will also install php7.2-common since it is a dependency.

On a machine without PHP 7.2:

sudo apt install php7.2-gd

Reading package lists... Done
[...]
The following additional packages will be installed:
  php7.2-common
The following NEW packages will be installed:
  php7.2-common php7.2-gd

and with PHP 7.2 installed:

sudo apt install php7.2-gd

Reading package lists... Done
[...]

The following NEW packages will be installed:
  php7.2-gd

Once installed, the GD config files will be created under /etc/php/7.2/(fpm|cli...)/conf.d and should be named xx-gd.ini.

These config files are loaded after your main php.ini and contain extension specific settings (in your case, GD settings).