I'm not sure if using a ternary operator inside map is considered un idiomatic, but it seems to work.

I'd say it's idiomatic, and can even be shortened since $_ is used as the default argument for many functions (including oct) and for regexes that aren't bound to something via =~:

use Data::Dump;
my @arr = qw/ 10 20 0b1101 0xF 023 /;
dd @arr;
my @converted = map {/^0/ ? oct : $_}  @arr;
dd @converted;

__END__

(10, 20, "0b1101", "0xF", "023")
(10, 20, 13, 15, 19)
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