Can new emotions be created or discovered?
The atlas of personality, emotion and behaviour catalogues over 3,000 emotions (Mobbs, 2020).  The atlas's approach taken to identifying and cataloguing the emotions was to start with existing lists of emotions and then using thesauri to identify synonyms and antonyms of emotions, which are themselves likely to be emotions. 

I expect that over time, existing emotions will be subdivided into more specific variants which will then need to accepted by the curators of each dictionary.  At the point these variants are included in dictionaries, the new emotion will be deemed to discovered.

Mobbs AED (2020) An atlas of personality, emotion and behaviour. PLOS ONE 15(1): e0227877. https://doi.org/10.1371/journal.pone.0227877