If you only require a PostGIS spatial data type, use the new Spatial Type parameter on the Create Enterprise Geodatabase geoprocessing tool when you create a geodatabase in PostgreSQL. If you specify PostGIS for the Spatial Type, you don’t have to configure the ST_Geometry type.
The Spatial Type parameter is available starting with ArcGIS Pro 2.9 and ArcGIS Enterprise 10.9.1 for use with on-premises PostgreSQL databases.
In earlier ArcGIS versions, geodatabase system tables in on-premises PostgreSQL databases required the ST_Geometry spatial type. So even if you used a PostGIS spatial type in your feature classes, you still had to configure the ST_Geometry library to create a geodatabase in PostgreSQL.
By removing the ST_Geometry requirement, ArcGIS can support on-premises PostgreSQL databases that cannot use the ST_Geometry type, such as EDB Postgres Advanced Server.
Additionally, when a geodatabase contains only the PostGIS type, you can use third-party tools to migrate it to a PostgreSQL-based database service offering in the cloud. That means moving your geodatabase will be easier if you later decide to migrate your ArcGIS deployment to the cloud.