1. For on-premise environments, go to:
DirSync | Environments | Filters | Advanced
2. Add an LDAP filter query, and click Save.
Example:
(|(&(objectClass=user)(memberOf=CN=Scoped Users Group,OU=Migration Scoped Users,OU=Migration Users,DC=aromerog,DC=tk)))
3. Validate the query in ADUCs Advanced Filtering to confirm the query returns only the objects in scope.

Note: Work with an AD Administrator if further assistance is required in writing the LDAP filter.
The Reconcile option might need to be enabled in the environment settings to clear previously ingested AD objects from the backend database.
For a cloud environment, there is a specific attribute filtering in which you can select the attributes and their values from within the DirSync Environment settings.