Yep, you'd have to be jailbroken / rooted to use Cydia.
Sorry, I must have been out of the loop. When was the jailbreak for iOS 13 published? (I'm also a complete stranger to jailbreaking—never done it before.)
A bootrom exploit has been found that works on all pre-2019 iOS devices.
Sometime in December, but Checkra1n is still in beta and only works up to the iPhone X since the bug was patched on the newer 2019 iPhones.