They can but a standard size fowl doesn’t usually start at peewee size just slightly smaller like a medium egg for example. I have seen a few examples where a few individuals had a really small egg in a standard size fowl on BYC. I’m guessing no bantam in your bunch? However mine did not start...
Color could be either but the weight might tell. RIR is large-xlarge and BR is large size. Weight class is determined by the average weight of a dozen eggs. Large 24 oz. x large 27 oz. How much does the egg weigh and if multipled by a dozen which class does it fit? :)