Some companies may not be familiar with CEFR and it may sometimes be safer to use descriptions such as "near native" or "fluent" (see e.g. Describing language skills on the Jobline LMU website). However, the Council of Europe (CoE) has pointed out that C2 is not meant to imply a near-native level:
Level C2, whilst it has been termed ‘Mastery’, is not intended to imply native-speaker or near native-speaker competence. What is intended is to characterise the degree of precision, appropriateness and ease with the language which typifies the speech of those who have been highly successful learners.
(Quoted from How Do You Prove Your Language Level? – The CEFR on the Linguacore blog; my emphasis. See also the Common European Framework of Reference for Languages: Learning, Teaching, Assessment: Companion Volume with New Descriptors from September 2017.)
Since many learners stagnate below C2, the market for tests that go beyond C2 is presumably exceedingly small. Nevertheless, the Level Guide on the Anglo-Link website contains a table with CEFR levels and the levels of three international tests: IELTS, the Cambridge English tests and TOEFL iBT. According to this table, the following tests or test results go beyond C2:
It seems that you can take (or retake) any of the above tests. If you can figure out what certificate future employers may be most familiar with, I would choose the test for that certificate.