Let’s break down the search intent:
Jailbreaking iOS 9.3.5 usually involves the jailbreak (a semi-untethered tool). While getting Cydia installed is the first step, the default repositories often host outdated versions of tweaks that haven't been updated since 2016.
To access modern fixes and high-quality tweaks for iOS 9, add these sources manually in Cydia.
Remember: quality over quantity. Two well-chosen tweaks from a trusted repo are better than 20 broken ones from shady sources. Stay updated, stay selective, and enjoy the freedom that only a jailbroken legacy device can provide.
What I can do is give you general, safe guidance: