Check here for correct values: https://www.din-formate.de/tabelle-papierformate-seitengroesse-din-a-masse-umrechnungstabelle-in-inch-zoll-fuss-ft-yard-yd-millimeter-mm.html
You can then enter the values and DPL will do as you want:
Downside is that you have to enter again and again - or create a partial preset for it.
Please note that the ratio changes a little from size to size, because the DIN A formats revolve around the square root of 2.
Crop A4 (297-210).preset (585 Bytes)