[southwestforests]

I wonder whether an apartment complex, a complex apartment, and an apartment with a complex, are similar enough to be the same thing.

Decades ago I built a styrene sheet, plasticard, model of the small apartment building I lived in to 1/285 scale, 1/300 scale, or something close and easy to do the math for to go with wargaming miniatures. Got elevation drawings via the office manager and worked from there. took doing some simple math to scale the measurements. Worked the size out on paper then drew it directly on the styrene sheet. Now, that was cut and glue individual panels as opposed to folding paper.

I have used poster paper for walls of O scale and G scale buildings. The, or an, 'old school' way I do things is for a 4-wall building start at edge of paper with drawing out the edges of one wall, using literal old school drafting triangles from school way back when.
Buildings of apparently complex shapes often can be knocked down to a series of boxes.

Having a ruler marked in dimensions for your chosen model scale sure helps. There are plenty in model train and in plastic model scales in imperial, I'm not sure about metric since we don't use that here.
With a scale rule a lot of math is avoided, just look at what the plans say, find that on your ruler, and there ya go.

Multiple intersecting pitched roof angles, well, that's another ballgame! One I try to avoid as much as possible.
But let's say the building has a hipped roof, not super simple but not too complex either. I'll look for a side elevation showing flat on the long side the full ridge line and lower edge of roof, which will give lengths of those. Then look for an end elevation where the distance along roof surface from edge to ridge can be measured. That will give the panel dimensions for two sides.
same profess can be followed to give measurements of hipped ends.

I hope that makes sense and eventually is useful to someone somewhere.