EnvelopeAggregate (geography Data Type)
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Returns a bounding object for a given set of geography objects. The resulting geography object contains multiple circular arc segments.
Syntax
EnvelopeAggregate ( geography_operand )
Arguments
geography_operand
Is a geography type table column that holds the set of geography objects on which to perform an envelope aggregate operation.
Return Types
SQL Server return type: geography
Remarks
A FullGlobe object is returned when the resulting bounding object is bigger than a hemisphere. This method is not precise.
Method returns null if the input has different SRIDs. See Spatial Reference Identifiers (SRIDs).
Method ignores null inputs.
Note
Method returns null if all inputted values are null.
Examples
The following example performs a EnvelopeAggregate on a set of geography location points within a city.
USE AdventureWorks2022
GO
SELECT City,
geography::EnvelopeAggregate(SpatialLocation) AS SpatialLocation
FROM Person.Address
WHERE PostalCode LIKE('981%')
GROUP BY City;