Normally, the app tries to make the text as large as possible but still fit on the available label space. However, with large labels (10 per sheet or less), and short addresses, this can make the text too large, for some people.
It is possible to scale down the text size for these label. After selecting the label sheet (10 labels per sheet or less), and viewing the print preview, tap the settings button on the top right.
The top setting – Font Scale, can be changed to reduce the text size from 100% downwards.