It looks like you are trying to use variable names stored in strings? This is not a very good thing to do, and you should probably reconsider.

However if you insist on doing that, you should look into symbolic references (see perlref). They only work with package variables, however (not those created with my). This seems to work:

my $test = "help";
our $help = 1;
no strict 'refs';
if(defined($$test)){ 
  print "defined\n";
};
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