For me this method is too user-specific (mostly when returning datetime strings rather than a date copy users can format as they want after that).
Every feature in Carbon needs unit tests (that's why codecov does not pass).
You also need to follow the code style of the project (check StyleCI details).
It's also required to use constats (
I agree with @Glavic for the macro label, this could go in our future list of macros.