You're probably in this forum because a WordPress Site Health Analysis provided a Recommended Improvement:
"Warning The optional module, Imagick, is not installed, or has been disabled." (FYI, the word "warning appears in yellow microprint and appears to be a yellow 'em-dash'; you can only see the term by copy/paste into a text editor.)
The ImageMagick extension, called Imagick when referring to the PHP extension, is a native PHP extension to create and modify images using the ImageMagick API. Do I/you need this??
I figured the easiest way to add the php extension would be through WHM -> EasyApache 4, but don't bother, Imagick is not there.
You can add it through WHM -> Software -> Module Installers -> PHP PECL -> (search) Imagick
But:
1) the latest version is 3.4.4 (2019-05-02)
"The 3.4.4 release is intended to be the last release (other than small bug fixes) that will support either PHP 5.x, or ImageMagick 6.x. The next planned release will be PHP > 7.0 and ImageMagick > 7.0 at least, if not higher."
[see:
http://pecl.php.net/package/imagick]
[see:
http://pecl.php.net/package-changelog.php?package=imagick&release=3.4.4]
2) Confusingly, the Imagick Extension description also refers to a similar name product - "ImageMagick" with a different version number; don't confuse these:
"Imagick is a native php extension to create and modify images using the ImageMagick API. This extension requires ImageMagick version 6.5.3-10+ and PHP 5.4.0+."
[see:
http://pecl.php.net/package/imagick]
3) I noted, through the above pathway and search, that Imagick 3.4.4 was installed in my php 7.2 folder [/opt/cpanel/ea-php72/root/usr/lib64/php/modules] but not my 7.3 folder. I remain hesitant to install it in 7.3 as it appears Imagick 3.4.4 is EOL and I have not found any Imagick 7.x versions.
Thus, I have decided not to install it in php 7.3 and will await the availability of the 7.x versions.