Unfortunately theme doesn’t have such option, you have to change source code manually. Modification below is described on Directory+ Theme.
In order to change lenght of displayed text on Category or Location pages, edit file
./wp-content/themes/directory2/portal/parts/item-container.php and look for following part of code:
Change truncate parameter to another number of displayed characters.
In order to change length of text on Search Results page, do the same change in theme file ./parts/post-content.php
Modification in our other directory type themes is basically the same, just some small differences in code may appear.