You can use the PlayerModel from Minecraft and even the BipedRenderer, but your are limited in what you can do with that.
I did just test it, you can use
RenderingRegistry.registerEntityRenderingHandler(FarmerEntity.class, (EntityRendererManager rendererManager) -> new BipedRenderer<>(rendererManager, new PlayerModel(modelSize, smallArms), shadowSize));
to register the BipedRenderer with the PlayerModel to your Entity.