Upper panel: Median intrinsic sizes(y-axis) of 50 μm in simulations as a function of stellar mass(x-axis) are shown. Middle panel: Evolution of mock IR photometric observational sizes at S/N =5. Lower panel: Evolution of ALMA observed sizes. The (≈0.01 − 0.02′′) angular resolution sizes are represented by the dotted lines and the low angular resolution (≈0.3′′) sizes are represented by the solid lines. The red scatter and the corresponding line show the CRISTAL Mitsuhashi et al. (2024) data and its best fit mass-size relation respectively.