How the heck does Barry Manilow manage to sing at live concerts with his mic two feet from his mouth? ,,,,With a band behind him? No doubt inears but still !!!
Good sound engineering, that is how.
In ear monitoring means no monitor in the field for the mic which means no feedback, plus Shure Beta85a gives 3 - 5db extra rear rejection.
You do notice some singers carefully control their dynamics and distance from the mic on stage ,
Up close and personal on the soft bits and standing further back when they lit rip .
Tom Jones claims to have blown up several studio mics in his day .
I did some choral recording one time , the Welsh male voice choirs were orders of magnitude louder than anything else , the acoustic power and resonance is quite something to behold .