Observations show that, at fixed stellar mass, galaxies were significantly more compact at high redshift than today, with massive spheroids at z ~ 2 having effective radii up to a factor of ~4–6 smaller than local counterparts, and disks also shrinking systematically with increasing redshift (Trujillo et al. 2007; van der Wel et al. 2014). ΛCDM-based models can grow galaxy sizes through minor mergers, inside-out star formation, and feedback, but they often require finely tuned merger histories and feedback efficiencies to simultaneously reproduce the strong size evolution of compact high-z systems and the more modest evolution of disks, leaving open debate about whether the standard framework naturally explains the full amplitude and diversity of the observed size–redshift relations (Hopkins et al. 2009; Conselice 2014).