Measurement of the branching fractions of the Cabibbo-favored decays $ {\mathrm{\Lambda }}_{c}^{+}\to \mathrm{\Lambda }{K}_{S}^{0}{K}^{+}$ and $ {\mathrm{\Lambda }}_{c}^{+}\to {\mathrm{\Xi }}^{0}{K}_{S}^{0}{\pi }^{+}$ and search for $ {\mathrm{\Lambda }}_{c}^{+}\to {\mathrm{\Sigma }}^{0}{K}_{S}^{0}{K}^{+}$

Based on $ {e}^{+}{e}^{-}$ collision data corresponding to an integrated luminosity of about $ 4.5\text{}\text{}{\mathrm{fb}}^{-1}$ collected at center-of-mass energies between 4599.53 and 4698.82 MeV with the BESIII detector, the absolute branching fraction of the Cabibbo-favored decay $ {\mathrm{\Lambda }}_{c}^{+}\to \mathrm{\Lambda }{K}_{S}^{0}{K}^{+}$ is measured to be $ (3.12\pm 0.46\pm \phantom{\rule{0ex}{0ex}}0.15)\times {10}^{-3}$. Combined with a previous measurement from the BESIII Collaboration, the branching fraction of the decay $ {\mathrm{\Lambda }}_{c}^{+}\to \mathrm{\Lambda }{K}_{S}^{0}{K}^{+}$ is calculated to be $ (3.07\pm 0.26\pm 0.13)\times {10}^{-3}$. The decay $ {\mathrm{\Lambda }}_{c}^{+}\to {\mathrm{\Xi }}^{0}{K}_{S}^{0}{\pi }^{+}$ is observed for the first time with a statistical significance of $ 6.6\sigma $, and its branching fraction is determined to be $ (3.70\pm 0.60\pm 0.21)\times {10}^{-3}$. In addition, a search for the decay $ {\mathrm{\Lambda }}_{c}^{+}\to {\mathrm{\Sigma }}^{0}{K}_{S}^{0}{K}^{+}$ is performed, and its branching fraction is determined to be $ (0.8{0}_{-0.24}^{+0.28}\pm 0.16)\times {10}^{-3}$, corresponding to an upper limit of $ 1.28\times {10}^{-3}$ at a 90% confidence level. These measurements provide new information that can be used to distinguish between theoretical models.