Thank you for your post.
At this time, the window size of the drop-down list cannot be sized. iOS will size the values to fit the window. If the window is still too large, then it will display as much as possible followed with ... to let you know there is more information.
You may want to try modifying the values in the value list to be shorter-yet still be recognizable as representing the longer statement and then use one of several possible methods to "look up" the full text from a related table.