Antiferromagnetic Order and Magnetic Frustration in the Honeycomb Heavy-Fermion System Ce(Pt${}_{1-x}$Pd${}_x$)${}_6$Al${}_3$: ${}^{27}$Al and ${}^{195}$Pt NMR Studies

Heavy-fermion systems with magnetic frustration offer a rich platform for investigating the interplay among Kondo screening, magnetic frustration, and quantum criticality. We report comprehensive ${}^{27}$Al and ${}^{195}$Pt nuclear magnetic resonance measurements on polycrystalline Ce(Pt${}_{1-x}$Pd${}_x$)${}_6$Al${}_3$ ($x=0$, 0.1, 0.2, and 0.3). For $x=0$, the Knight shift, linewidth, and nuclear spin-lattice relaxation rate reveal a paramagnetic heavy-fermion ground state persisting down to 0.1~K, characterized by a coherence temperature $T_{\mathrm{c}\mathrm{o}\mathrm{h}}\simeq 15$~K. Substituting Pd induces antiferromagnetic order at $T_{\mathrm{N}}\simeq 3.5$~K, while suppressing $T_{\mathrm{c}\mathrm{o}\mathrm{h}}$. Comparison between $x=0.1$ and $x=0.3$ reveals a crossover from itinerant spin-density-wave antiferromagnetism to more localized-moment antiferromagnetism, indicating a shift toward the localized side of the Doniach phase diagram. These findings establish Ce(Pt${}_{1-x}$Pd${}_x$)${}_6$Al${}_3$ as a tunable platform to explore the competition between Kondo screening and magnetic frustration.