Thanks for contacting support.
As per my understanding, you need to perform search text in both uppercase and lowercase. If so is the case, then please try using following regular expression.
// In order to search a string in either upper case or lowercase, you may consider using regular expression.
textFragmentAbsorber = new TextFragmentAbsorber("(?i)Line", new TextSearchOptions(true));
In case you have different requirement, please share some further details, so that we can reply accordingly.