Hello,

You can modify the tempdb size by going to the properties (right click Tempdb and properties); change the initial zise and the growth; The values should take effect when you restart SQL services.

Also, check these commands:

USE master;

GO

ALTER DATABASE tempdb

MODIFY FILE (NAME = tempdev, SIZE=<size of the data file>);

GO

ALTER DATABASE tempdb

MODIFY FILE (NAME = templog, SIZE=<size of the log file>);

GO

Restart SQL services for the changes to take effect....