What's the opposite of "enlarge"?
Solution 1:
There's nothing wrong with using "shrink" as an antonym for "enlarge" in this context. If "enlarge" bothers you, you might try pairing "shrink" with "expand".
Solution 2:
The antonyms are reduce or shrink, depending on the meaning. For example if the space is enlarged, it may be reduced to its initial size.
Solution 3:
"ensmall" perhaps? Shrink is the correct word, it shouldn't feel wrong.