1. Communities can have separate OWD through Default External Access.

2. Role Hierarchy can be set using “Number of partner roles” under Community Settings.
Note: Maximum Number of partner roles can be set to 3. Executive, Manager and Worker roles.

3. Sharing Rules can be created. Supports both Criteria Based and Owner Based sharing rules.

4. Sharing Sets can be used – https://www.infallibletechie.com/2016/09/what-is-use-of-sharing-set-in.html

5.  Owner of the account(Channel Sales Manager – Usually an internal Salesforce user with full Salesforce license) have access to all the records associated to it.

6. Account Relationships and Account Relationship Data Sharing Rules- https://www.infallibletechie.com/2020/02/account-relationships-and-account.html.