how do I create a curved shape guide line

[MACE5cm]

for printing, it is necessary to create a template for designers that will contain a bend for mockups of the cup of the desired shape. to prevent this bend from being accidentally printed, it is necessary to create a guide line that cannot be accidentally included in the print.

[MACE5cm]

I also don't see the guide lines from pdf files that I used to do in sllustrator

 

[GarryP]

Guides in the Affinity applications can only be straight horizontal lines or straight vertical lines.

You can create a curve (or line) for snapping/alignment purposes but you will need to remember to hide it before exporting/printing.