Chamfering is a fancy word for an angled edge, and it makes ordinary lumber look extraordinary. I rout this profile all the time on outdoor projects I build. The 2 1/4″ chamfer bit you’ve found will work fine. I really think you’ll like the results.
Where can I find a really large chamfer bit for a router? You’ve written about 2 1/2” diameter bits used to make outdoor wood structures look better, but all I can find is 2 1/4”.