This is the most straightforward approach. If you want to see someone's posts, send them a friend request. If they accept, you'll have full access (subject to their friend-specific privacy settings). If they don't accept, you have your answer: they don't want you seeing their content. Respect that.
Attempting to bypass privacy settings is a violation of boundaries.
No random, free website on the internet has the technological power to breach Facebook's servers and extract private data. If a security flaw that massive existed, professional hackers would sell it for millions on the black market—they wouldn't give it away on a free website covered in pop-up ads. How "Free Private Profile Viewers" Actually Work facebook private profile viewer free
Facebook does not provide third-party developers with access to private user data through its Application Programming Interface (API).
By being aware of the risks and taking necessary precautions, you can protect yourself and have a safer online experience. This is the most straightforward approach
Disclaimer: This article is for informational purposes only. We do not encourage or condone illegal activities or the violation of user privacy. If you'd like, I can provide more information on how to: against phishing attempts.
To understand why no free viewer exists, you need to understand how Facebook handles private data. If they don't accept, you have your answer:
The answer should be no.
If a loophole or glitch ever allowed outsiders to view private profiles, Facebook’s security team would patch it within hours.