Electrical transport measurements in heterostructures of antiferromagnetic Cr2O3 bulk crystals and a thin Pt layer exhibit sharp responses as the N\'eel vector of the Cr2O3 undergoes the spin-flop transition. This abrupt change can arise from several distinct mechanisms including magnetostriction, proximity-induced anomalous Hall, spin Hall anomalous Hall, and spin Hall planar Hall effects. While large Pt devices sensing multiple up/down domains can produce indistinguishable Hall signal jumps due to different initial N\'eel vector orientations, smaller Pt devices that sense single domains isolate the proximity-induced Hall signals. This allows direct electrical detection of N\'eel vector reorientation across the spin-flop transition in single domain regions. Furthermore, the single-domain state can be prepared by magnetic field cooling or magnetoelectric cooling. We demonstrate a method to control and characterize almost the three-dimensional orientation of single-domain N\'eel vectors by exploiting Hall measurements and cooling techniques, crucial for future antiferromagnetic spintronic applications.