My personal plan for the first gun is no carvings. I want to focus on getting the various pieces to interact properly....everything aligned correctly, get the architecture as close to right as I can, etc. At most I'd want to try a wooden patch box or a simple brass one, but maybe neither.
RCA21 is a not a heavily carved or adorned gun, but it is a Berks style.
I'm a huge fan of Berks guns, and also a Berks County PA native. I happen to have an early Reading gun as well as a later Reading/Berks style gun, contemporary rifles, that I own and shoot. So I have some well-made examples to reference in-hand. Not originals, but they're solid examples for reference.
But my personal goal is the layout and architecture. The carving on 21 is pretty minimal, too.
I've just heard a lot that Lancasters are best for beginners. I sure don't intend to dive in to a Lehigh out of the gate, but 21 seems like it'd be attainable.
I guess worse comes to worse, if I bungle it up pretty good, I use the stock for my kids to make smores in the fire pit and I get a new hunk of maple and try again...?