Computer Configuration > Administrative Templates > Google Chrome > Extensions
Both
HKLM\Software\Policies\Google\Chrome
Setting the policy specifies which extensions are not subject to the blocklist. A blocklist value of * means all extensions are blocked and users can only install extensions listed in the allow list. By default, all extensions are allowed. But, if you prohibited extensions by policy, use the list of allowed extensions to change that policy. Example value: extension_id1 extension_id2