How can I make my pitch sound more mature?

I have a pretty wide range...I can sing tenor...up until mezzo soprano comfortably...But my pitch changes dramatically as I go higher...While when I'm lower, I sound more mature...while my higher notes still sound like I'm 15...UNLESS I got into what I call "black girl mode"...that I sort of change up my vibrato...and it has somewhat of a churchy sound to it...But for example, say I don't want it sound churchy...I just want it to sound mature....is there anyone way to do thaaat?