With this project you have a template to create a collection project that measures curve radius like in roads, using only three points. You could set this up in a project for QField or MerginMaps using a connected GNSS receiver or the built in GPS in a mobile device.

The project only use the first three points in a line to calculate the radius. Less than three points in a line will not result in a radius.

Some more info in the project metadata.