There was a product range called P.I.C.K., still available (although not the whole range, unfortunately), which is for building interior scenes. It uses real world dimensions (so doors are a standard size). It does not have scale options in the parameters, if you want to rescale them you have to use the drag option, wich is not very accurate.

Anyway, this is largely unusable now (even though I believe it ships with Poser) as to use it you need to resize every DAZ character to fit. Most scenery content is made to visually fit the current figures (although some scenes are way oversized), so visually scaled to M4 V4.

If you really want to know how tall your characters are, measure them in the scene. You set your own units in preferences, don't you? I use cm, some use inches... load a figure, load a primitive cone, rotate on the Z axis 90 degrees so the tip of the cone touches the floor between your figure's feet, then drag the cone up the Y axis until the tip touches the top of your character's head. Read how far you have moved up the Y axis, and that's the height. M4 is about 6'7" from memory.

The main issue is proportion. M4 V4 use 'heroic' figure proportions (head about 1/8th overall height, or 8 heads tall rather than the more conventional 7 heads tall). K4 uses more accurate proportions, but load a K4 next to M4 and compare the sizes of their heads... fat headed baby! This occasionally leads to weird looking scenes if you mix characters (gen 3, gen 4) as they are proportioned differently.

I know all this, but I don't really care that much. The figures look fine as they are for most things. I know what to adjust if I want a specific, high accuracy scene like some soppy family portrait where relative proportions are important.