The Importance of Culture Trickling Down From the Top Down

Can a creative, not in senior leadership working in an awful culture actually affect change? And if so, how? Sure. So the point of culture trickling down from the top down is key because at some juncture, there's a vital conversation to be had with someone very senior. But ultimately, it's up to the person to decide, is this enough? Am I truly flowering or am I actually floundering?