I've heard that 12.5:1 is usually ideal for making power
that totally depends.

max power on many engines is closer to 13:1, and some engines like more fuel in some regions, that's why dyno tuning results in best power gain rather than widebanders simply trying to hit a particular AFR.

also despite the base fuel map being close, intended target is often different from actual achieved target... even if you get all your trims perfect, power enrichment might still not be what you expect.

a major mfr like gm usually aims for somewhere between 11:1 and 12:1 on stock calibrations to prolong engine life during abuse at the expense of a minimal power loss, and also as a safety threshold to keep the engine alive in event of mechanical problem, sensor inaccuracy, inconsistent fuel quality, engine production differences, etc.