Always use strict; use warnings;. You'd have gotten several warnings that would have indicated that subroutine parameters are not specified that way in Perl.   Try this:

use strict;
use warnings;

my @array=qw(one two three);
my $arref=\@array;

sub func 
{
    my $aref = shift;
    
    $aref->[0]="four";
}

&func($arref);

print "@array";
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