Default Cydia repos do not have all the latest tweaks and packages compatible with the latest iOS version. Therefore you have to add new repos in Cydia Sources to have access to all latest stuff. I am posting here a list of the top Cydia repos which have latest packages. You can follow this step by step guide on How to add new repo in Cydia?
One of the best Cydia repo is thebigboss repo. It has access to hundreds of themes and tweaks. Please check the below list and add any repo you want.
Best Cydia Sources & Repos for iOS 12 & iOS 13
These are some of the old and well-known Cydia Sources with thousands of tweaks and themes. You can browse different categories/sections related to packages.
ModMyi Repo: http://apt.modmyi.com iHacksRepo: http://ihacksrepo.com iPhoneCake Repo: http://cydia.iphonecake.com InsanelyiRepo: https://insanelyi.com BiteYourApple Repo: http://repo.biteyourapple.net SinfuliPhone Repo: http://www.sinfuliphonerepo.com
TheBigBoss repo is one of the best Cydia sources that stores thousands of themes, layouts, and tweaks. You can find almost every new and old tweak that you are looking to install on your iDevice. BootLogo, Keyboard themes, Homescreen Icons, Lockscreen Icons and a lot more.
Best Sources With Latest & Free Tweaks:
The below list of Cydia Sources will give you access to almost all new tweaks compatible with iOS 12 & iOS 13. You will be able to download all these tweaks for free, and won’t need to pay a single penny for them.
Karen's Repo: https://cydia.akemi.ai/
Packix repo: https://repo.packix.com
Limneos repo: http://limneos.net/repo/
CoolStar Repo: https://repo.coolstar.org/
UnlimApps Repo: https://beta.unlimapps.com/
c1d3r Repo: http://c1d3r.com/repo/
Chariz Repo: https://repo.chariz.io/
Another best repo is HackYouriPhone repo. HackYouriPhone repo has unlimited tweaks, themes, and packages to customize the complete look and feel of your iOS device. Here I have written a complete guide on How to add Hackyouriphone repo in Cydia Sources?