Sustainable protection of lithium (Li) metal anodes (LMAs) is crucial for enhancing the cycling stability of Li–sulfur (Li–S) batteries under lean-electrolyte conditions. However, sporadic and severe Li pitting during initial Li stripping induces uncontrollable structural evolution at the LMA interface, which compromises the durability of protective layers through delamination and deformation, often leading to early electrolyte depletion. In this study, we exploit a dual-layered protective layer (DPL) that reinforces interfacial adaptivity against such detrimental evolution during cycling. Our work aims to offer comprehensive guidelines for DPL design through careful control of material composition, processing parameters, and compositional balancing. Among various factors, it is critical to reduce the total thickness and rebalance the layer structure by thinning the adhesive inner layer and relatively thickening the mechanically robust outer layer. The optimized DPL architecture improves both adhesion and mechanical compliance, resulting in enhanced interfacial stability and effective suppression of electrolyte decomposition. Consequently, the DPL enables significantly prolonged cycling performance of Li–S full cells, even under lean-electrolyte conditions, achieving over 200 cycles with 80% capacity retention when combined with advanced electrolytes. Cross-optimized DPL offers a rational design framework that may serve as an optimal template for the future LMA protection strategies in practical Li–S cells.