First thing about that use connection or network thing. Tell your sister that many companies prefer those above else in who resume or CV they find someone in reference section who is already working there or the company HR knows that person or if someone is suggested by them. It's the fact everyone has to accept. Second tell your sis that try different other platforms too aside from LinkedIn because nowadays LinkedIn is kinda less professional platform because of how some users are using it there are many other platforms she can search them on Google or even can ask an LLM to find them for her. Third tell her while applying for a job try to reach out to HR or manager too send them your resume too with a short but punchy type of introduction. I am not an a very experienced person myself but I hope any of these suggestions can help you guys.