Currently minecraft has a limit of six layers on a banner. Most recipes exceed this limit. Internally, minecraft does support an almost unlimited number of layers.

I propose that on prison to increase the number of layers to something more reasonable.

There is a Spigot plugin that is able to do exactly this:
https://www.spigotmc.org/resources/better-banner.16432/

There may be others with more features.

This plugin supports multiple tiers so different donor ranks can be granted more layers.

MVP - 10 layers & copy up to 10 layers
Supreme - 12 layers & copy up to 12 layers
god - 15 layers and copy up to 15 layers
Titan - Unlimited layers and copy unlimited layers

 

Mineverse doesn't have anything to do with layers on banners, minecraft limits it.

 

Exactly.... That's why I said:

And that's why I'm proposing they add a plugin to increase the layers.

It's amazing what plugins can do.