Texture Overlay/Layer Rendering [1.18.2]

[MWR]

I'm making a mod where you can add a small 4 by 4 emblem to your armor. I want to add multiple symbols, but it can get tedious to create a texture for each emblem. Also, I plan on adding the ability make your own emblems with patterns, similar to banner patterns.

I looked at the code for rendering banner patterns, but I can't understand it. I know you can add layers to item model JSONs, like the spawn egg, but they're not dynamic. I thought of combining the two images and making a temporary texture while the game runs, but is there a more elegant way to achieve this?

Edited June 29, 2022 by MWR
I realize that I can't combine textures and the best way is to add another render layer.

[MWR]

After a lot of digging, I've concluded the best way to go about this is not combining textures, as that is impossible during runtime, but to add a render layer. I've been trying to understand how the rendering works, but I don't know what buffers are, like this one in HorseMarkingLayer:

public void render(PoseStack p_117058_, MultiBufferSource p_117059_, int p_117060_, Horse p_117061_, float p_117062_, float p_117063_, float p_117064_, float p_117065_, float p_117066_, float p_117067_) {
      ResourceLocation resourcelocation = LOCATION_BY_MARKINGS.get(p_117061_.getMarkings());
      if (resourcelocation != null && !p_117061_.isInvisible()) {
         VertexConsumer vertexconsumer = p_117059_.getBuffer(RenderType.entityTranslucent(resourcelocation));
         this.getParentModel().renderToBuffer(p_117058_, vertexconsumer, p_117060_, LivingEntityRenderer.getOverlayCoords(p_117061_, 0.0F), 1.0F, 1.0F, 1.0F, 1.0F);
      }
   }

If this is a Java question, let me know, but any help is appreciated!