Q&A for How to Jailbreak an iPhone

No, a jailbreak for iOS 10.2.1 has not yet been developed. I do recommend you stay on that software version. You never know when a jailbreak will be ready.

It doesn't work on evasi0n7, but it works on Pangu.

No it won't. You need your passcode to be able to jailbreak. I suggest visiting an Apple store.

You can jailbreak your device without a PC or Mac, but it depends on your iOS version. For older versions, you can use untethered jailbreaks like p0sixspwn or Pangu. For more recent versions, semi-untethered jailbreaks like Dopamine may work. Some exploits, such as palera1n, may be challenging or impossible without a computer, so explore options like unc0ver that don't require another device.