I have seen college level coursework, when the student's selected from the competency offerings for each course which competency they wanted to apply to their rubric.
However, I cannot think of a systemic way of doing this in Moodle.
You could include on the course summary page - a list of each of the competencies. Then add within the course a quiz activity with a single select one question. Each of competency is listed and the student "declares" which competency value is their goal upon course completion.
When the course is successfully completed, the instructor can award the requested competency value.
You would still need to build or the competency framework and relate them to the course. Consider how to build out your scales for the competencies before you implement. Such as; Submitted evidence for this competency, no submitted evidence, alternative evidence was submitted.