Only rule I know of, is that the 10 sons are to be recited in 1 breath;
Given that albeit the Ba’al Koreh can be Motzi the Tzibbur their obligation of Megillah reading, yet he cannot be Motzi their Chiyuv of 1 breath, hence several Shuls have the Minhog for all the congregants to recite the 10 sons in their own 1 breath before the Ba’al Koreh repeats it, much as is done by the other 4 verses recited by the congregation & then repeated by the Ba’al Koreh.
It is lamentable that this beautiful Minhog has not been universally adopted by all congregations.