Computer Configuration > Administrative Templates > Google Chrome > Privacy Sandbox policies
Both
HKLM\Software\Policies\Google\Chrome
A policy to control whether the Privacy Sandbox Site-suggested ads setting can be disabled for your users. If you set this policy to Disabled, then the Site-suggested ads setting will be turned off for your users. If you set this policy to Enabled or keep it unset, your users will be able to turn on or off the Privacy Sandbox Site-suggested ads setting on their device. Setting this policy requires setting the PrivacySandboxPromptEnabled policy to Disabled.