Thanks, guess I have to use Translate, then … and some wacky hacks:
Created a plane with 5 cm radius = 10 x 10 cm
Current width = 10cm
Target width = 12cm
Needed extra width = 12-10 = 2 cm
Select left edge of plane
Input this: gx0.02
Current height = 10cm
Target height = 12cm
Needed extra height = 7-10 = -3 cm
Select top edge of plane
Input this: gy-0.03