The present problem investigates 3D flow over an expanding wedge geometry of a tangent-hyperbolic Casson fluid. A two-phase approach considers a liquid phase and a dusty fluid, while a Darcy–Forchheimer law is used to model this fluid flow to capture motion and heat transfer. The several aspects are based on variable thermal radiation, heat sink effects, and slip conditions applied. A tri-hybrid nanofluid comprising silicon dioxide, copper, and aluminum oxide nanoparticles suspended in ethylene glycol, the base fluid, is incorporated into the analysis. The derivation of nonlinear ordinary differential equations (ODEs) is used to characterize momentum, thermal behavior, and fluid motion under these circumstances. ODEs are formulated using similarity transformations and slip conditions. The finite element approach is employed. It is estimated that the fluid phase on the heat transfer rate and skin friction coefficient is higher than the dusty phase on the Nusselt number and skin friction coefficient. The heat transfer rate for ternary hybrid nanofluid is larger than that for hybrid nanofluid.