Meta (formerly Facebook) services can be blocked in the /etc/hosts file by adding entries that redirect their domains to 0.0.0.0 or 127.0.0.1.  
Tip: Use 0.0.0.0 instead of 127.0.0.1 to avoid timeouts if no service is running on localhost.
🔁 After editing, restart your network or flush DNS cache (sudo systemd-resolve --flush-caches on Linux).

Use the following entries in /etc/hosts to block Meta’s core services:
0.0.0.0 www.facebook.com
0.0.0.0 facebook.com
0.0.0.0 login.facebook.com
0.0.0.0 www.login.facebook.com
0.0.0.0 fbcdn.net
0.0.0.0 www.fbcdn.net
0.0.0.0 fbcdn.com
0.0.0.0 www.fbcdn.com
0.0.0.0 static.ak.fbcdn.net
0.0.0.0 static.ak.connect.facebook.com
0.0.0.0 connect.facebook.net
0.0.0.0 www.connect.facebook.net
0.0.0.0 meta.com
0.0.0.0 www.meta.com
0.0.0.0 instagram.com
0.0.0.0 www.instagram.com
0.0.0.0 www.instagram.com
0.0.0.0 whatsapp.com

The most effective approach is to use a comprehensive blocklist or manually add key domains and subdomains:

Recommended Blocklists
Steven Black’s hosts list: A widely used, curated list that includes Meta domains and is regularly updated. 
https://github.com/StevenBlack/hosts
Ultimate Hosts Blacklist: A unified list that covers Meta services, ads, malware, and tracking domains. 
https://github.com/Ultimate-Hosts-Blacklist/Ultimate.Hosts.Blacklist
GitHub: Block Twitter/Facebook in your /etc/hosts: A ready-to-use list specifically for blocking Meta and Twitter.
https://gist.github.com/djaiss/85a0ada83e6bca68e41e