If you're still wondering, you can't JB iOS 13.5.1.
However if you have a pc you can downgrade to iOS 13.5 because it's still signed, but do it asap because it might get unsigned soon. (get the version at ipsw.me)
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To jailbreak, you need a pc.
After that you need iTunes,iCloud and AltServer installed in your pc. (install and set em all up)
Connect your device and check for a diamond icon (altserver) in your system notification area at your taskbar.
Right click the icon and choose install Altstore, then choose your device.
After installing altstore you can go ahead and download Unc0ver from the site and wait for it to download the ipa file, copy it to altstore and voila just press jailbreak in Unc0ver.
Hope it helps, also alot of youtubers has a much more detailed info on how to do it so yeah I recommend watching some vids.