Photoionisation models predicted R_Fe as a function of the ionisation parameter and hydrogen density. Left: Models with a subsolar metallicity of Z/Z_⊙ = 0.2 plausible for BLRs of low-luminosity AGNs observed by JWST. Right: Models with a super solar metallicity of Z/Z_⊙ = 2 plausible for BLRs of local AGNs as well as high-luminosity quasars observed in SDSS. In both panels, the mean R_Fe of JWST identified AGNs is indicated by the solid red contour, and the mean R_Fe of SDSS AGNs is indicated by the dashed blue contour.