Research the Jailbreak
If you're jailbroken or plan to jailbreak your device at some point, you'll want to be careful with iOS 10.3.3 and dig into current jailbreak information before you go ahead with the installation.
Jailbreak developers recently released a iOS 10.2 jailbreak to the public but it's not clear when, or even if, another jailbreak tool will arrive.
Developers have also cracked the iOS 10.3.1 update but there's no guarantee they'll release a tool for everyone to use.
Rumors indicate that we could see an iOS 10.3.1 jailbreak emerge in the near future but nothing is confirmed. For now, you must contend with older jailbreak tools.
The public iOS 10.2 jailbreak is available for devices like the iPhone 6s, iPhone 6s Plus, iPad Pro, iPad Air 2, iPad mini 4, and iPhone SE. However, it's missing in action for older iPhone models like the iPhone 5.
If you want to jailbreak an older device you must be on iOS 9.3.3 or something older. Sadly, there's no way to downgrade to an older version of iOS.