If you want to print a single large label that fills an entire A4 or Letter page (e.g., a poster, sign, or full-page product sheet), set your template to match the page size.
Steps
Go to Templates → click Create product label template.
Click Configure (top right):
Brand: Custom
Model: Sheet label
Rows: 1, Columns: 1
Sheet size: A4 (210 × 297 mm) or Letter (216 × 279 mm)
Click Save.
Design your label — you now have the full page as your canvas.
Print Settings
Paper size: A4 or Letter (match your template)
Scale: 100%
Margins: None or Minimum
Most printers have a small unprintable margin (3-5mm) around the edges. Your content may be slightly clipped at the borders. If this is a problem, keep important elements away from the page edges.