You can use CloudLinux Selector to enable GD extension in PHP via Plesk.
1. Log in to your Plesk account.
2. Click on the Pull icon in the right sidebar and choose PHP Selector.
3. Under the Account Global Settings, go to the Extensions tab.
Note: If it shows an error related to the Native PHP version, change to a non-Native PHP version first.
4. Checkmark the GD. Once enabled, it will display a success message.
The message will read that the module GD is saved.
Note: This tutorial covers enabling the GD module on all domains. To enable it for an individual domain, go to Per Domain Settings, click on the Per Domain option, and then select GD for the domain you wish to enable it on.
The message will read that the module GD is saved.