Win8 Strawberry 5.8.9.5 (32)  Sat 06/11/2022 15:18:47
C:\@Work\Perl\monks
>perl

use strict;
use warnings;

my $str = '\x{aF}';

my ($hex_digits) = $str =~ m{ [[:xdigit:]]+ }xmsg;
my $hex_number_in_decimal = hex $hex_digits;

print "'$hex_digits' == $hex_number_in_decimal decimal \n";

^Z
'aF' == 175 decimal