Providing value for Data Store through custom properties file

Not entirely sure about Data Store, but while passing the admin console setting in the customization file, we can pass the values of the Data Source like this

## Administration Console Setting: Data Source
## Name: jdbc/LegacyDB
## Valid types: MySQL, MariaDB, Oracle, SQL Server, PostgreSQL, DB2
dataSource.935f04f8-e8ac-449f-8410-d9ac13cac74e.USERNAME=db.user
dataSource.935f04f8-e8ac-449f-8410-d9ac13cac74e.PASSWORD=1234abcd
#dataSource.935f04f8-e8ac-449f-8410-d9ac13cac74e.TYPE=
#dataSource.935f04f8-e8ac-449f-8410-d9ac13cac74e.CONNECTION_STRING=

Data stores must be manually configured in Admin Console after import.

You can only deploy the data store as part of application package. Properties file don’t support Data Stores customisation.

For Data Souce as kapil suggested you can import properties file in Admin Console