M–R relations for five representative NS EOSs: APR, ENG, H4, SLy, and WFF (Lattimer & Prakash 2001; Özel & Freire 2016; Lattimer 2021). Different colors correspond to different EOSs. For this study, we restricted our analysis to two magnetar masses, M = 1.4 M_⊙ and M = 2.0 M_⊙, indicated by the horizontal dashed black lines. Observational constraints from PSR J0740+6620 (yellow band; Fonseca et al. 2021) and PSR J0348+0432 (blue band; Saffer et al. 2025) are shown in the figure.