In this study, we apply the dual-component model of \(\gamma \) -ray emission to assess the validity of the unified scheme for high-luminosity radio sources, specifically, Fanaroff–Riley Type II radio galaxies (FR IIs) and Flat-Spectrum Radio Quasars (FSRQs). We analyse a combined dataset comprising 220 FSRQs detected by the Fermi Large Area Telescope (Fermi-LAT) and 107 non-Fermi detected FR IIs. Utilizing the concept of relativistic beaming, we compute both the extended and core \(\gamma \) -ray emissions and used the \(\gamma \) -ray beaming factor ( \(g_\gamma (\beta , \psi )\) ) to estimate the \(\gamma \) -ray core-dominance. Our main findings are as follows: (1) Radio ( \(R_r\) ) and \(\gamma \) -ray ( \(R_\gamma \) ) core-dominance parameters (in logarithmic scale) range from −2.40 to 4.32 and −1.63 to 9.73, respectively, for FSRQs, with mean values of 1.36 and 2.52. In contrast, for FR IIs, \(R_r\) and \(R_\gamma \) span −3.30 to 0.27 and −1.82 to 3.79, with mean values of 0.16 and 0.23, respectively. The significantly lower core-dominance of FR IIs compared to FSRQs, supports the unified model, wherein FR IIs represent the misaligned counterparts of FSRQs. (2) \(\gamma \) -ray emission in FSRQs is predominantly core-dominated, exceeding the contribution from the extended region by approximately three orders of magnitude. Strong anti-correlations between \(R_r\) , \(R_\gamma \) and their respective emission components further indicate that \(\gamma \) -ray production is substantially influenced by relativistic beaming effects. (3) Distribution of FR IIs in the parameter space of \(R_r\) and \(R_\gamma \) vs. \(\gamma \) -ray emission suggests the presence of varying beaming effects across different regions. These findings indicate that \(\gamma \) -ray emission in FSRQs originates primarily from the core and reveals the contributions of relativistic beaming effect to the unified model of high luminosity samples of FSRQs and FR IIs.
