The $R{T}_3{\mathrm{B}}_2$ ($R=\mathrm{Y},\mathrm{Lu}, T=\mathrm{Co},\mathrm{Os}$) family hosts a perfect kagome lattice of $T$ atoms, offering an interesting platform to investigate the interplay of electronic structure, superconductivity, and lattice dynamics. Here, we compare two members of this family, ${\mathrm{LuOs}}_3{\mathrm{B}}_2$ and ${\mathrm{YCo}}_3{\mathrm{B}}_2$, with similar crystallography but differing chemical composition, which results in different electronic structures and correlation signatures, as well as distinct spin-orbit coupling effects. We confirm superconductivity in ${\mathrm{LuOs}}_3{\mathrm{B}}_2$ with $T_c=4.75\mathrm{K}$, while ${\mathrm{YCo}}_3{\mathrm{B}}_2$ remains nonsuperconducting above 1.8 K. Both materials exhibit kagome-derived electronic features, including quasiflat bands, Dirac cones, and van Hove singularities. Fermi surface calculations reveal a highly anisotropic electronic structure in ${\mathrm{YCo}}_3{\mathrm{B}}_2$, establishing a $k_z$-selective metallic behavior and leading to strongly suppressed in-plane conduction, in contrast to the more isotropic fermiology of ${\mathrm{LuOs}}_3{\mathrm{B}}_2$. Phonon calculations for ${\mathrm{LuOs}}_3{\mathrm{B}}_2$ show imaginary modes, indicating potential lattice instabilities. Experimental estimates of the Wilson and Kadowaki-Woods ratios point to significant electronic correlations in both compounds.

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• Charge density waves
• Electron-phonon coupling
• Kagome metal
• Density functional theory