We report the hydrostatic pressure induced two topological phase transitions in strong spin-orbit coupled material at room temperature. Frequencies of the and phonons are observed to increase monotonically up to , but with a clear slope change in mode at . Interestingly, there are two clear anomalies noticed in phonon linewidths of mode at pressures and . Such anomalies are evidence of isostructural electronic transitions associated with unusual electron-phonon coupling. The high-pressure synchrotron powder diffraction and Raman show a first-order phase transition above 4 GPa. First-principles density functional theory-based calculations of electronic band structure, topological invariant and mirror Chern number reveal that the phonon anomalies at and are linked to the band inversions at and points of the Brillouin zone respectively. The first band inversion at point at  GPa changes the from 0 to 1 leading to the transition of system into a topological insulator. The second band inversion at point at results in , revealing a transition to a topological crystalline insulating state. Therefore the applied pressure systematically tunes the electronic states of from a normal semiconductor to a topological insulator and finally into a topological crystalline insulator at two distinct pressures of and respectively, before undergoing a structural phase transition at .