That's a picture of my UI, and I'm curious if there is an addon to change the font / size / location of the number on my potions / healthstone / mage food ("consumables")
I doubt there is a specific addon for that. You could possibly change it in the LUA settings tho.
However, you want the number centered and smaller I assume? Just put an actionbar (through Bartender4), set XX% transparacy (like you have atm) and put it in there. Then you'll end up with a centered smaller number.
Not sure what that bars addon is but I know if you redid it with dominos you can resize specific bars. Probably the same with barkeep but never used it myself.