I wanted to search inside a PDF with Adobe Acrobat Reader for MacOS (or the one built in with MacOS). I want to search, for example, for the capital letter "U".
Is it possible and, if yes, how?
A tutorial online here for Adobe Acrobat Reader indicates in step 4 how to do a case-sensitive search, which is what you're looking for.
Ctrl-F to start a search in Adobe Acrobat Reader. Enter the letter
U and then tick (select) the check-box next to "Case-Sensitive" search. Press the
Search button to start the search.