[wffurr]

There's Cydia: https://cydia-app.com/

And if you have a Mac, you can build and install apps on your own device with Xcode. No Apple developer paid account required.

AltStore does something similar by signing IPA files with your personal key: https://altstore.io/.

[easrng]

The site you linked to (hxxps://cydia-app.com/) is unofficial, links to piracy and spyware sites, and should not be trusted. The official Cydia site is https://cydia.saurik.com/ but it doesn't include much information about Cydia and jailbreaks. To find out what jailbreaks are available for your device, check the r/Jailbreak wiki. (https://www.reddit.com/r/jailbreak/wiki/ios/canijailbreak)

[judge2020]

A better 'how to jailbreak' is https://canijailbreak.com/ which is ran by some well-respected community members https://justapengu.in/about

[wffurr]

Thanks, too late to edit. Wasn't obviously a scam when I first looked at it.