A free mod for Mount & Blade II: Bannerlord, by ClearanceClarence.
The CC’s Banners mod adds 48 new color choices to the game’s banners. The mod’s developer had this idea for a long time but has been unable to get it done due to their lack of knowledge on how to use the Mod Tools.
It’s fairly simple and only requires you to install it. The way it works is that you will need to download it from the Chrome Web Store. Once you have it installed you can use it by clicking “New Banners” on the main menu. You will then be presented with a list of all the available banners. If you are looking for a specific one you can find it in the list.