Actually you are able to set the diagram zoom level to an arbitrary value (for example let's say ~ to 115%)
See this page for details:
https://sparxsystems.com/enterprise_architect_user_guide/13.0/modeling_tools/appearance_options_diag.htmlTry like this:
- Use Ctrl+mouse wheel to zoom in a little bit more than 100% (say ~ to 115%)
- Then from the ribbon, select Design -> Diagram -> from the Manage dropdown list -> Properties
- In the dialog click Diagram.
- Finally click the "Set as Default" button
Then each time you will open the diagram, you will see that the zoom level you've set will be respected.