Terraria has default 3 sizes of saints, 1(small), 2(medium), and 3(large).
You can change it by the following procedure
1. Shut down the server
2. Open the server back up
3. Click on Configuration Files
4. For the file "serverconfig.cfg" click on the button "Configuration Editor
5. In the "World Site" field, enter the number of the specified size
6. Click on "Save and exit"
7. Start the server

