Modern product management operates within organizational structures characterized by functional specialization, matrix reporting lines, and distributed accountability. Despite being responsible for strategic prioritization and cross-functional alignment, product leaders frequently lack formal hierarchical authority over engineering, marketing, finance, or operations. This paradox—high accountability without direct control—creates structural tension that can either undermine performance or catalyze high-impact influence. This paper develops an organizational design framework for cross-functional authority without formal control. Drawing from resource dependence theory, social capital theory, structural contingency theory, and contemporary matrix governance models, the study conceptualizes product leadership as influence architecture rather than positional power. It identifies mechanisms through which product leaders establish legitimacy, align incentives, structure decision rights, and manage conflict in complex digital enterprises. The paper proposes comparative organizational models that enable high-impact product leadership within non-hierarchical environments and introduces a maturity framework for scaling influence systems. The findings contribute to both organizational theory and executive practice by reframing authority as a function of alignment design rather than reporting structure.