How do I change my album artwork size

So I have iTunes 12.4.3.1, and I'm using an iPhone 5 SE...or whichever one the newest one is.

Is there any place in iTunes that I can go to adjust my album artwork size so that it fills the entire allotted space? A lot of times the album art only covers like 60% of it or so, and I'd like everything to be one uniform size. So is there anywhere where I can input dimensions or even a manual resizer or anything where I can tell iTunes to fill the entire space for artwork when it uploads my music?

Danke!