I want to update my iphone 6 in ios 13

It is not possible to update that model to iOS 13. The highest possible is iOS 12.5.5.

You might need it, but you can't do it, sorry, because of hardware (CPU/RAM) incompatibility.

See this list:

Sorry - but that is not going to happen. Max iOS on a 6 is 12.5.5

Update to IOS13

I need iOS 13 in my apple 6