Can iPhone 6 Plus support IOS13

Sorry no.

iOS 13 needs 2 GB RAM or more and Apple A9 processor or later.

Your iPhone 6 Plus has only 1 GB RAM and Apple A8 processor.

Sorry, no.

Are you sure you don't have a 6s Plus ?

That model CAN run iOS 13.x

Chattanoogan wrote:

Are you sure you don't have a 6s Plus ?

That model CAN run iOS 13.x

If that's the case OP would not have asked the question.