There are many companies that make several drawing templates that have the file extention *.drwdot. The other option can also be to create a bunch of different title blocks and let the user decide which sheet size he or she wants and Solidworks will choose the title block for you based on what is available. Both options depend on how many templates you will have. If you have a lot templates, then it is easier to make just the title blocks (sheet formats) and let SolidWorks assign a sheet size to them.
Basically, when you open up a new drawing and Solidworks asks you for a sheet size, the number of sheet sizes will depend on what title blocks you have saved. Let me illustrate- the picture below shows the standard items available when you open a new drawing.
Then I will just take any of the sheet formats (*.slddrt) and save it to a folder on the desktop. It can be any folder in any server. You will have to go into the Options>System Option>File Locations and change the location of the “sheet formats”.
Once that is done just go to file open and open a new drawing. The window should look like this (if you only have one sheet format saved out).