The best feature to use to achieve this requirement is sharing sets. Sharing sets allow the developer to grant access to records for external users based on a common account or contact. In this case, the developer can create a sharing set that grants access to the cases for the external partners who have the same account as the support team. Role hierarchy, criteria-based sharing rules, and Apex managed sharing are not suitable for this scenario, as they are not available for external users with Customer Community Plus licenses. Reference: [Sharing Sets], [Sharing Architecture], [Trailhead: Sharing and Visibility Basics]