In this application you can replace the given/when with a dispatch table. Other changes you can make since you use v5.36;:

• You no longer need use strict; -- this is implied by use v5.12; or above;
• You can use the experimental for-list syntax, though for the moment you will need to silence the "experimental" warning;
• You can either eliminate the no if ... or just disable the warnings for smartmatch unconditionally, depending on whether you use them elsewhere in your code.

The each() built-in is discouraged because there is only a single iterator for a given hash, which can be reset in un-obvious ways -- see the docs for each() for details.

My take on your boilerplate, with all the above incorporated, is:

#!/usr/bin/env perl

use v5.36;     # was 'use 5.010;'
#use warnings; # unnecessary now!
#use strict;   # unnecessary since 5.12.
no warnings 'experimental::for_list';
#no if $] >= 5.018, warnings =< "experimental::smartmatch";
use Getopt::Std;
my %opts;
getopts( 'hvi:', \%opts ) or die "getopts failed\n";
my $verbose;
my $infile;
for my ( $k, $v ) ( %opts ) {
    state $dispatch = {
	h => sub { ...; },
	v => sub { ++$verbose; },
	i => sub { $infile = $_[1]; },
    };
    my $code = $dispatch->{$k}
	or die "*** BUG: no handler for -$k.\n";
    $code->( $k, $v );
}

Note that the subroutines in the dispatch table do not close over your loop variables, so you must pass them in explicitly.