Love it. I do this all the time. At work, I have a fearless male alter-ego (I am a woman). His name is Chad. If Chad would do it (ask for a promotion, give his opinion without hegdging), that’s what I try to do.
In my personal life I don’t have an alter ego (that just seems silly, hah). I am currently changing my life in somewhat terrifying ways, so I make my decisions as if I am the bravest version of myself. I have lots of “oh my god, am I really going through with this?” moments but I am so much happier than the more cautious version of myself. I have yet to ever regret acting brave when I wasn’t.