The standard scaling is 28mm which fits the vast majority of miniatures on the market.
Many DnD minis (including our own) are 28mm scaled but it depends on the company. Games Workshop for example are at 32mm these days.
If you were printing OpenLOCK tiles and wanted the standard 25mm square to be 32mm then you would increase it by 28%
I collect mainly for my homebrew DnD campaign and dont scale any of the pieces up, though it depends on your model collection