The paginate() method takes a parameter for the number of entries to show per page. Given that, you could just have a drop down form that has 5, 10, 20, etc as values and use that value to get the number of entries.
<select name="perPage">
<option value="5">5</option>
<option value="10">10</option>
</select>
$perPage = $request->input('perPage', 10);
$users = App\User::paginate($perPage);
The above will use the value from perPage, or default to 10 if not present.