Some users look toward jailbreaking as a way to "force" apps onto older firmware. While tools like Cydia allow for tweaks that can bypass version checks, this is generally not recommended for the average user. Jailbreaking can expose your device to security vulnerabilities and may cause stability issues on older hardware.
To get Messenger on a device running iOS 9.3.5, you typically need to trigger Apple's "Last Compatible Version" feature: Messenger Ios 9.3.5 Download
Devices permanently stuck on 9.3.5 include: Some users look toward jailbreaking as a way
It is important to remember that if you successfully install a legacy version of Messenger, you will be using a version from several years ago. This means you will likely miss out on newer features such as: Encrypted "Secret Conversations" Advanced AR filters and stickers Modern group video calling features Recent UI updates and dark mode To get Messenger on a device running iOS 9