In addition to being able to use Managed Search APIs for managing clusters and collections, you can use Solr APIs for operations such as indexing documents and searching, with a few exceptions.
Authentication and Authorization
Note the following about authentication and authorization:
Authentication – Authentication relies on the client app having an OAuth2 access token for Solr in Managed Search. This access token is distinct from the OAuth2 access token for Managed Search operations.
Authorization – There is no per-customer or user-specific authorization. After authentication, an app can access all Solr APIs except for some that are excluded.
Excluded Solr APIs
To ensure ease of management and stability of Managed Search clusters, some Solr APIs are excluded.