From type/Dateish

See Original text in context

method dd-mm-yyyy(str $sep = "-" --> Str:D)

Returns the date in DD-MM-YYYY format (ISO 8601). The optional positional argument $sep, which defaults to -, is a one-character separator placed between the different parts of the date.

say Date.new("2015-11-15").dd-mm-yyyy;    # OUTPUT: «15-11-2015␤» 
say DateTime.new(1470853583).dd-mm-yyyy;  # OUTPUT: «10-08-2016␤» 
say Date.today.dd-mm-yyyy("/");           # OUTPUT: «14/03/2020␤»