@Ral-Clan Just tried this and it works fine on AmgiaOS4.
Use the Screens applications found in Prefs and add a screen of your chosen resolution and name it MultiView.
Set the MultiView tooltype PUBSCREEN=MultiView.
Now MultiView will open up on the specified screen when started.
I also just tried setting MultiView ToolType FONTSIZE=32 and it opened the document with the default font in the bigger size on workbench. No need to set FONTNAME.
Mind you this is on AmigaOS4. You may get different results on OS3 if that's what your using.