Is it an actual line or start and end points?
If it is a line check this post.
https://community.esri.com/t5/arcgis-survey123-blog/survey123-tricks-of-the-trade-lines-and-polygons...
But big note here try this offline. I found that if you are offline and have no basemap you cannot collect lines at all. It is a major bummer. I am trying to get the 123 team to include generic basemaps for this. For us we gave up on it since the packages are a pain Instead we use Field Maps to collect the lines, generate an id with Arcade, then use launch links to send that key to the form that is a related record. Best of both worlds then. You could do this linking in Quickcapture also but not sure it does lines.
If you just want the distance between a start in end I use this formula in the form. (this is where you are vs Design)
round(acos(sin(${LatitudeWGS84} * pi() div 180)*sin(${DesignLatitudeWGS84} * pi() div 180) + cos(${LatitudeWGS84} * pi() div 180)*cos(${DesignLatitudeWGS84} * pi() div 180)*cos((${DesignLongitudeWGS84} * pi() div 180)-(${LongitudeWGS84} * pi() div 180))) * 6371000,2)
I also have an Arcade version of this formula if you need it that works in Field Maps. We use it mostly to give warnings when a crew is too far from the place they were supposed to be.
Hope that helps