Label is a tweak for jailbroken iOS 11 and 12 devices that allows you to change various labels around iOS's interface. Currently only supports changing the text, but changing the colour is also a planned feature.
The tweak is currently available on the BigBoss repo for free.
Send me a DM on Twitter (@Archergs14) or an email (archergsdev@gmail.com) if you are interested in contributing directly. Feel free to fork the repo to make your own changes, however I ask that you give credit to the original developer (me) if you release a tweak based upon it. A guide will be added on how to contribute to the repo soon. In the meantime, clone the repo and make the changes you want to make, then let me know you're ready to push your code. Theos and the iOS 11.2 SDK is required to build the tweak.