Actually you can't do this from the SQL statement, but you can perform this with the powershell/cmd

powershell -command "Restart-Service MSSQLSERVER -Force"

You can use xp_cmdshell system procedure to call any command line to stop; however, you definitely can't start it because how will you execute a command using T-SQL while you are not connected (service is stopped)?

using the command line or powershell .

net start MSSQL$instancename

net stop MSSQL$instance

using SSMS

SHUTDOWN -->wait and shutdown

SHUTDOWN WITH NOWAIT --> dont wait and shutdown

Don't think there is a straight way you can startup in T-SQL, you probably have to do something like this.

You can't directly start or stop SQL Server itself using SQL statements, you can perform tasks related to database management, such as starting, stopping, and restarting individual databases within SQL Server using SQL statements.