I'm looking at videos of people jping in gtm and the armour is purple and pink I was wondering what mod/texture pack it is so I could use it also the katana and hotbar I found this through one of C8G's videos so if he could tell me it would me a big help Image of what I'm talking about https://imgur.com/gallery/vrLtUOO
It is a custom resource pack that a gtm player made. You can make your own or you can download a few from this channel.
People with a bit of resource pack knowledge have modified the GTM resourcepack to be colored. Yes, as others mentioned, Chirag is one such RP modifier. There are others, but Chirag is one of the only few who made their work public.
It's really not that hard. The only limiting factor is that GTM has custom models which means the resource pack works a bit differently. The only thing you can really change is the color unless you know a bit of java and how to edit the Json files that come with the pack.