You can enable additional PHP modules on your account as follows:
1. Login to cPanel
2. Goto "Select PHP Version"
3. Make sure you're not on the native PHP version from the dropdown, and click set as current if you need to change it
4. Make sure you're on the php extensions page, or click the Switch to PHP Extensions link.
5. Select the modules you want to enable and then click save
The modules will now be available under your cPanel account