I honestly think the fake it til you make it thing is not always the way to go. The best experiences I've had in the room was when i didn't try to change myself to fit the role, but when i presented myself as is and let the interviewer decide whether or not i fit. Don't try to tell people what you think they want to hear, just tell them what you want to say. And be done with it. If you fit, you fit. If you don't eventually you will somewhere. Know it all answers don't play well imo. And neither does acting like you got the role before you even leave the room. It's impossible to know what questions are coming next. Once you get past the tell me about yourself the last thing you want is the interviewer to keep going back to their question list. Just have a conversation like your having a cocktail with the person. Because that's all it is until you get to the technical part. Then flex your chops