EngineMode
The engine mode for the domain. Valid values are GENERAL (the standard OpenSearch engine) and OPTIMIZED. If you don't specify an engine mode, GENERAL is used. OPTIMIZED requires OpenSearch 3.5 or later, OpenSearch Optimized instance types (OR1, OR2, OM2, or OI2) for the data tier, and is available only for the OBSERVABILITY use cases. The engine mode can't be changed after the domain is created.