The condsurv package contains a function for generating conditional survival estimates with associated confidence intervals, and a function for plotting conditional survival curves.
This package is documented using pkgdown, and the resulting website is available at http://www.emilyzabor.com/condsurv/, where detailed Tutorials can be found covering all of the package functionality.
See http://www.emilyzabor.com/condsurv/reference/ for detailed function documentation.