I'd like to be able to put a "numeric" or "string" in front a var to let it know what I want

You can. They are spelled "0+" and "''." respectively.

my $x = '8';
my $y = '16';
print((0+$x) | (0+$y), "\n");    # 24
print((''.$x) | (''.$y), "\n");  # 96
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Update: Oops, that doesn't quite answer your question. If the variable wasn't read-only, you could do the following:

$x .= '';  # Stringify
$x += 0;   # Numerify
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