Survey123 is a very powerful app, and I have dep[cloyed it for numerous purposes and projects.
I think to even extend its currently capabilities is to allow the creation of polygons and poly lines.
in the Connect form when adding a feature type you should be able to select point,line, polygon.
This idea has been marked as a duplicate of Improvement idea for survey123: create lines and polygons by Scott Prindle. Please consider visiting this idea to vote and comment.