If you attempt to install Imagick for PHP 8.0, the installation will fail.
At this time, the software Imagick has not been updated yet to be compatible with PHP 8.0.
The last update that has been seen was from their development team on 05/02/2019.
3.4.4 stable 2019-05-02 imagick-3.4.4.tgz (247.5kB)
PHP 8.0 was released on November 26, so it appears it is not compatible with the current version Imagick available. Sources indicate an update is being developed for the use of PHP 8.0, but there is no ETA for when that would be ready for the latest version of PHP.
Currently, there is no workaround for adding Imagick for PHP 8.0. If you need to used Imagick for your content, then you will need to use a lower version of PHP such as PHP 7.4 or 7.3.