Sometimes, some sites get blocked by the administration and in case facebook gets blocked and you need to use it then you can use proxy apps to run facebook app.
Different apps are available on playstore, You just need to download any proxy or vpn app from there and can connect facebook and run it easily. Popular apps are:
- Hotspot Shield Free VPN
- ProtonVPN Free.
Now when you install the app in your phone and open it. It will ask you to connect it with wifi or internet. After making the connection as shown in below image, you can run facebook in your area even it is blocked.