It is certainly possible to export 3D content from Revit Architecture to STL format for 3D printing, but this is not typically done for the templates (.rlt) but from .rvt (project) or even .rfa (family) files.
You can, of course, use the templates for making new projects and then export the finished content to STL format, it just does not make sense for the template alone, and it is unlikely a direct rft to stl conversion is even feasible as an export or file conversion.
Updated: February 5, 2024