how to reduce font size so "contacts" fit on labels

Hi clickker,

welcome to the Apple Community.

Wondering which app you are using to create the address template. ?

With the app open, see if you can choose "Show Fonts" from the "Format" menu in the top menu bar.

Then select the text you want to change, and experiment with the different text sizes in the small font window you opened.

Or, if it helps:

Seems you can print addresses directly onto labels from contact cards / groups of cards in the Contacts app.

Apple support have an article online to help with that.

Print mailing labels, envelopes and contact lists in Contacts on Mac

https://support.apple.com/en-au/guide/contacts/adrbab40ca1d/12.0/mac/1

All the best :-)