Scale/fix a QR code size on the printer lable

Hi all,
after a long time of discussions I got a Zebra ZD421 QR code printer for our Tulip apps.
But after studiing the ZPL language refs, I can’t believe that it is not psossible to print different f.e. serial numbers to a fixed qr code field.
The size of the printed QR code depends of the length of the printing data. So if there are a lot of information to print, the QR code field grows and can’t printed complete on the lable :-/

How do you handle this?

Yes, there is a ZPL parameter to scale the QR code, but than I have to check evers information / serial numbers before printing.

Regards Chris