Explanation:
Box 1: Yes
The azureADOnlyAuthentication (bool) property is not present.
If set to true then Azure Active Directory only Authentication enabled.
Mixed authentication will be supported.
Box 2: No
We see sku tier is Standard.
Azure SQL databases with the Standard tier do not support autoscale. Autoscale is a feature available in the Serverless compute tier of Azure SQL Database, where resources scale automatically based on workload demands. The Standard tier, part of the provisioned compute model, requires manual scaling or the use of Elastic Pools for resource sharing and scaling.
Box 3: No
The first line of the BICEP template would have to be like:
resource managedInstance 'Microsoft.Sql/managedInstances@2021-11-01-preview' = { Reference:
https://learn.microsoft.com/en-us/azure/templates/microsoft.sql/managedinstances?pivots=deployment-language-bicep
https://learn.microsoft.com/en-us/azure/azure-sql/managed-instance/create-bicep-quickstart

Change automated backup settings for Azure SQL Database
You can modify automated backup settings for Azure SQL Database, such as the short-term retention policy and the backup storage redundancy option that's used for backups.
To change differential backup frequency, select 12 Hours or 24 hours from the drop-down menu under Differential backup frequency.
Step 1: Go to the logical server in Azure with the databases whose retention period you want to change.
Step 2: Select Backups on the left pane, and then select the Retention policies tab.
Step 3: Select the databases for which you want to change the PITR backup retention. [Select db2] Step 4: Select Configure policies from the action bar.
Step 5: To change the retention period for point-in-time restore backups, use the slider under Point-in-time restore. [Skip] Step 6: To change the PITR (point-in-time recovery) backup retention period or the differential backup frequency for active databases by using the Azure portal: [Skip]

Step 7: In Long-term retention, Monthly LTR Bakcups, Set Keep the first backup of each month for: 5 Years Question: The monthly backups must be retained for five years, and then deleted.
Reference:
https://learn.microsoft.com/en-us/azure/azure-sql/database/automated-backups-change-settings

Automatic tuning options
The automatic tuning options available in Azure SQL Database and Azure SQL Managed Instance are:
* FORCE LAST GOOD PLAN (automatic plan correction)
Identifies Azure SQL queries using an execution plan that is slower than the previous good plan, and forces queries to use the last known good plan instead of the regressed plan.
* Etc.
You can either manually apply tuning recommendations using the Azure portal, or you can let automatic tuning autonomously apply tuning recommendations for you.
Azure defaults are set to FORCE_LAST_GOOD_PLAN enabled.
We need to disable it.
With transact-SQL:
ALTER DATABASE SET options (Transact-SQL)
Parameters include:
<automatic_tuning_option> ::=
{
AUTOMATIC_TUNING ( FORCE_LAST_GOOD_PLAN = { DEFAULT | ON | OFF } )
}
Solution with T-SQL
Stored procedure execution
You can use the SQL Server Management Studio (SSMS) user interface or Transact-SQL in an SSMS query window to execute a stored procedure. Always use the latest version of SSMS.
Use SQL Server Management Studio
Step 1: In Object Explorer, connect to an instance of SQL Server or Azure SQL Database, expand that instance, and then expand Databases.
Step 2: Expand the database that you want, expand Programmability, and then expand Stored Procedures.
Step 3: Right-click the stored procedure that you want to run [here: ALTER DATABASE SET] and select Execute Stored Procedure.
Step 4: Set the parameters: AUTOMATIC_TUNING ( FORCE_LAST_GOOD_PLAN = { OFF } ) Step 5: Select OK to execute the stored procedure. If the stored procedure doesn't have any parameters, just select OK.
Reference:
https://learn.microsoft.com/en-us/azure/azure-sql/database/automatic-tuning-overview
https://learn.microsoft.com/en-us/sql/t-sql/statements/alter-database-transact-sql-set-options
https://learn.microsoft.com/en-us/sql/relational-databases/stored-procedures/execute-a-stored-procedure