WSS allows customers to fully enforce Google's Safe Search mode regardless of the client browser's configuration. When WSS policies are managed from the portal, Portal Admin's can configure this from the Portal > Policy > Content Filtering > Search Restriction. The feature is explained here.
This option is removed from the portal when the policy is managed from the Management Center. The Safe Search policy has to be configured on the MC and then push it to WSS in case of UPE.
WSS UPE (Universal Policy Enforcement) Tenant
The Safe Search policy has to be configured on the MC and then push it to WSS in case of UPE.
Things to note before installing the policy.
Installing the CPL policy to Enforce Google SafeSearch