This » PECL extension is not bundled with PHP.
Information for installing this PECL extension may be found in the manual chapter titled Installation of PECL extensions. Additional information such as new releases, downloads, source files, maintainer information, and a CHANGELOG, can be located here: » https://pecl.php.net/package/luasandbox.
If the operating system is Debian 10 or later, or Ubuntu 18.04 or later, then
LuaSandbox should typically be installed from the package
php-luasandbox:
sudo apt-get install php-luasandbox