I see you are in the US and am assuming that you mean US standard duplex outlets.
You really don't need any official drawings as the dimensions are all in English units (inches) and are totally based on nominal fractional sizes.
Each D shaped hole has a 1 5/16" basic diameter with 1 1/8" between the two straight sides. They are spaced 1 1/2" apart. The mounting hole is centered between them and is for a #8 countersunk, flathead screw.
The outside rectangle is usually about 2 3/4" x 4 1/2" but can vary. Going smaller than that size may leave some wall openings exposed, but many styles of cover plates are larger. Steel plates, intended for metal equipment in a commercial/industrial environment often are smaller as such equipment often has tighter tolerances on the cut out size.
These numbers are for the cover plate and are based on slightly smaller dimensions of the actual duplex outlets. The center to center spacing, of course, is a constant. Tolerances and allowances are generous so you really can not go wrong.
Make it fit.
You can't win and there is a penalty for trying!