Hi,
I think this:
you can create 2 textarea (alias: textarea_full and textarea_intro), textarea_full is visible on profile,edit page and registration, textarea_intro is hidden on profile,edit and registration.
When user fill and save your profile you can add in textarea_intro truncated text of textarea_full with our triggers. Also you can truncate the textarea_full is you want a maximum lenght.
In list user you can render the field textarea_intro.

You can do this:
- Download, install, and enable our skeleton plugin, you can find here: https://www.easy-profile.com/docs/44-triggers.html
- Go in /plugins/jsn/skeleton/skeleton.php and remove the function: triggerFieldAvatarUpdate and triggerProfileUpdate
- add this function to file:

triggerFieldTextare_fullUpdate($user,&$data,$changed,$isNew){

   // textarea_full max lenght - 250 characters

   if( strlen($data['textarea_full'])>251 ) $data['textarea_full']=substr($data['textarea_full'],0,250);

   // fill textarea_intro - 100 characters

   if( strlen($data['textarea_full'])>101 ) $data['textarea_intro']=substr($data['textarea_full'],0,100).'...';

}

NOTE: this code is not tested and not supported, only serves to give you an idea