Exact size of the mesh

How I may do this?
For example - I wish to create plane with 2:3 correspond. For example one side will be 20 points and the other is 30 points.
So is it any hotkey? I press “N” - there only medians, not size.

There’s a button with the text ‘Edge Length’ in ‘Mesh Tools 1’

Also the in object mode the ‘Transform Properties’ window will show the scale X/Y/Z, which also can be used for scaling the object how you want

The default plane is 2 Blender units by 2 Blender units. If you were [in Top view] to Grab one edge and type Y 18, and then Grab the other edge and type X 28 = you get your 20 by 30…

THat’s what I look for. I looked in edit mode )
THanks you all:spin::spin::spin::spin:

in edit mode go to the edit buttons window and look for a panel labeled “Mesh Tools 1”
here there are options for activating display of additional information such as edge length and face areas, which may be more accessible than the transform properties window.