Yes there are many 6 months diploma courses

1. Diploma in digital marketing

2. Diploma in graphic design

3.Diploma in web development

4. Diploma in data science

5.Diploma in cyber security

You can choose according to your interest and domain

Diploma courses are generally short term courses its duration is between 3 months to 24 months.commonly it is specialisation in one subject in which you are deeply interested.there is 6 month course in iitms india Diploma In Mass Communication in different area a) Elements Of Management b) Public Relations c) Journalism d) Mass Communications Media..