This present work emphasizes the numerical modeling of lead-free methylammonium tin tri-iodide (MASnI3)-based perovskite solar cells (PSCs) under optimizing preconditions. The prior selection of the perovskite material of MASnI3 is feasible for a more extended absorption spectrum due to a smaller bandgap of 1.3 eV than higher bandgap methylammonium lead tri-iodide (MAPbI3)-based PSC and the factor of lesser toxicity. Furthermore, to enhance the efficiency of the device, selecting potentially steadier and superior carrier transport materials (CTMs) is among the most effective approaches for optimizing device outputs. Among the proposed materials, a prior selection of copper antimony sulfide (CuSbS2) and zinc oxide (ZnO) as CTMs with an optimized thickness of MASnI3 material has offered a higher power conversion efficiency (PCE) of 22.16% under the photoillumination AM1.5. Furthermore, the less-defective PSC device can also be helpful for further device optimization and futuristic development.