TIMTOWTDI but here's an illustrative test. See also How to ask better questions using Test::More and sample data

use strict;
use warnings;

use Encode 'encode';
use Unicode::Char;
use Test::More tests => 2;

is to_bytes ('0x03C0'), 'CF80', 'Code point to bytes (0x format)';
is to_bytes ('U+03C0'), 'CF80', 'Code point to bytes (U+ format)';

sub to_bytes {
    my $u = Unicode::Char->new;
    (my $in = shift) =~ s/^(?:0x|U\+)//;
    return uc unpack 'H*', encode 'UTF-8', $u->u ($in);
}
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Translating bytes to code points is left as an exercise.