@Antonio Elias Soares Ferreira da Silva
The Azure portal does not have a dedicated column that shows the size of databases by default. However, you can view the size of a single database in the Metrics blade, where it is listed as Total Database Size. Please check the below doc for further details.
https://learn.microsoft.com/en-us/azure/postgresql/flexible-server/concepts-monitoring
Regards,
Oury