iOS 13.5.1 downgrade is no longer possible. Apple is no longer signing iOS 13.5.1, a week or so after it released iOS 13.6 to the public. That now means that it is impossible to downgrade from iOS 13.6.
Here's how to jailbreak iOS 13.5.1 using checkra1n on compatible iPhone and iPad models, complete with video tutorial.
You can now no longer have iOS 13.5.1 downgrade ability after Apple stops signing iOS 13.5 jailbreak friendly firmware. Here are the details.
You can now downgrade iOS 13.5.1 to jailbreak iOS 13.5 while Apple is still signing the firmware. Here are the details on this.
Looking to jailbreak iOS 13.5.1 or iPadOS 13.5.1 update? Well it has now been confirmed that Apple has patched the unc0ver iOS 13.5 jailbreak with the new update. Here are the details on this.