Size–mass relation of BGGs classified using the consensus (color+sSFR) method, shown across six redshift bins from z = 0.08 to z = 3.7. Blue circles represent star-forming BGGs, and red hexagons show quiescent BGGs. The dashed and solid lines indicate best-fit power-law relations for SFGs and QGs, respectively, with shaded bands showing 1σ uncertainties. Cyan dashed-dotted and orange dotted lines show comparison relations from Faisst et al. 2017, while dashed lime and dashed magenta lines show van der Wel et al. 2014 results. Gray vertical and horizontal lines represent the stellar mass limit of log₁₀(M_*/M_⊙) > 10 and size cut of R_e > 0.5 kpc, applied when fitting size-mass relation. The BGGs generally follow similar evolutionary trends but are slightly smaller at fixed mass, especially among quiescent centrals, highlighting the impact of group environment on galaxy structure.