No, you can use the backward-compatible syntax if you don't want to spend any time porting to the newer improved syntax.
https://docs.perl6.org/language/regexes#Perl_5_compatibility...
http://design.perl6.org/Differences.html#New_regex_syntax
https://docs.perl6.org/language/5to6-nutshell#Add_:P5_or_:Pe...