A quick google search found this tip on reddit; tested and works.
1) Open the unit artdef file in notepad
2) cntrl+f and type "missilecruiser"
3) just above and to the left of the first instance of missile cruiser is 1.000000. That # controls the size. I went with 2.200000, which is between a destroyer and battleship. Make sure to save before closing. Works on games in progress.
Apologies to original poster, I didn't see a name.
1) Open the unit artdef file in notepad
2) cntrl+f and type "missilecruiser"
3) just above and to the left of the first instance of missile cruiser is 1.000000. That # controls the size. I went with 2.200000, which is between a destroyer and battleship. Make sure to save before closing. Works on games in progress.
Apologies to original poster, I didn't see a name.