I am trying to figure out how to program one extension to not be able to make long distance calls. If I change that extensions COS to lets say 5, does that automatically restrict it? Do I need to do anything else?

You will have to set deny table for cos 5 I.e 00 in deny table will block international calls

I wouldn't use 5, because you might need other restrictions. Try COS 3. In your TRS tables, you put 1xxx in restrictions and in any table that includes 3 you put 1800,1888, etc into exceptions.

As long as you're restricting, be sure to put 0xxx into the table and you can get fancy by making sure you deny first digit * and # CLASS codes.

Carl