Hello .
Can I say "variety topics" without word "of" ?
I mean can I use "variety" as an adjective ?
Thank you in advance for attention .
No
Thank you , but what about (variety show) in this link :
variety show - definition of variety show by the Free Online Dictionary, Thesaurus and Encyclopedia.
You will see in the definition in that link that 'variety' is used in a different way from that in your original question. You can have a variety show and a comedy show; you can have a variety of shows - musical, comedy, variety, etc; you cannot have 'a variety shows' meaning 'several different kinds of shows'.