Nope, Apple generally locked down systems to that they can't boot OSes older than they are. The last eMac to be able to boot directly into OS 9 was the 2003 "ATI Graphics" 800 MHz/1GHz eMac. Every eMac newer than that is incapable of booting into OS 9.

Any PPC is capable of running OS 9 apps in "Classic" mode in OS X, though. (Requires OS X 10.4 or prior, as the Classic environment was removed in 10.5.)