Yes. There is a zoom feature on the Offline toolbar, or use Ctrl+Mouse Wheel within the Ladder View to zoom in/out.
If you want to make the base 100% font size larger (or smaller), in the DmDesigner1_2.ini file (launch it from LaunchPad Applications group), look for the [Fonts] group and change the Workspace Font from Arial:10 to Arial:11 (or whatever). After editing/saving the .INI file, shut down Designer and relaunch it.