The　main　purpose　of　this　study　is　to　investigate　the　thermal　behavior　of　power　law　fluid　within　a　plus-shaped　cavity　under　the　influence　of　natural　convection,　also　taking　into　account　the　Darcy　number　and　magnetohydrodynamics　(MHD).　The　problem　is　formulated　as　a　system　of　partial　differential　equations　considering　the　power　law　fluid＇s　rheological　behavior.　The　left-side　walls　are　maintained　at　a　specific　low　temperature　while　the　lower　and　the　right-side　walls　have　uniform　maximum　temperatures.　The　boundary　condition　is　designed　to　enhance　heat　transfer　efficiency　within　the　cavity,　utilizing　advanced　thermal　insulation　methodologies.　Finite　element　method　(FEM)　simulations　are　conducted,　and　a　grid　independence　test　is　performed　to　validate　the　results.　The　impact　of　relevant　parameters　on　the　variation　in　momentum　and　thermal　distributions　is　investigated　using　streamline　and　isothermal　contour　plots.　The　results　indicate　that　as　the　Rayleigh　number　increases,　the　kinetic　energy　also　increases,　whereas　the　viscosity　and　circulation　zones　expand　with　an　increase　in　the　power　law　index.　The　Nusselt　number　exhibits　a　higher　value　in　the　shear-thinning　case　(n　=　0.7)　compared　to　the　Newtonian　(n　=　1)　and　shear-thickening　(n　=　1.2)　cases.　This　empirical　observation　underscores　the　vital　role　that　fluid　rheology　plays　in　molding　the　overall　heat　transfer　performance　within　the　cavity.　The　study　concludes　that　there　is　a　distinct　correlation　between　the　heat　transfer　rate　and　the　Rayleigh　number　(Ra).　As　Ra　increases,　there　is　a　significant　improvement　in　the　heat　transfer　rate　within　the　flow　domain.　Furthermore,　the　fluid　behavior　and　heat　transfer　performance　within　the　cavity　are　significantly　influenced　by　the　presence　of　magnetohydrodynamics　(MHD)　and　the　Darcy　effect.